| Transactions |
| Date | Team | Player | Type | OthTm | EffDate | When |
| 3/27/2012 | Bal | Adrianza | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Anderson | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Avila | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Beckham | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Blanks | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Britton | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Brown | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Carrasco | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Clemens | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | DeWitt | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Elbert | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Gomez | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Gose | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Hughes | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Hunter | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Iglesias | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Lawrie | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Litsch | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Matusz | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | May | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | McNutt | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Miller | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Moustakas | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | O'Sullivan | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Porcello | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Saunders | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Sipp | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Smoak | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Stewart | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Weeks | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Wood | Acquired via trade | Bos | | After |
| 3/27/2012 | Bal | Zimmermann | Acquired via trade | Bos | | After |
| 3/27/2012 | Bos | Adrianza | Traded away | Bal | | After |
| 3/27/2012 | Bos | Anderson | Traded away | Bal | | After |
| 3/27/2012 | Bos | Avila | Traded away | Bal | | After |
| 3/27/2012 | Bos | Beckham | Traded away | Bal | | After |
| 3/27/2012 | Bos | Blanks | Traded away | Bal | | After |
| 3/27/2012 | Bos | Britton | Traded away | Bal | | After |
| 3/27/2012 | Bos | Brown | Traded away | Bal | | After |
| 3/27/2012 | Bos | Carrasco | Traded away | Bal | | After |
| 3/27/2012 | Bos | Clemens | Traded away | Bal | | After |
| 3/27/2012 | Bos | DeWitt | Traded away | Bal | | After |
| 3/27/2012 | Bos | Elbert | Traded away | Bal | | After |
| 3/27/2012 | Bos | Gomez | Traded away | Bal | | After |
| 3/27/2012 | Bos | Gose | Traded away | Bal | | After |
| 3/27/2012 | Bos | Hughes | Traded away | Bal | | After |
| 3/27/2012 | Bos | Hunter | Traded away | Bal | | After |
| 3/27/2012 | Bos | Iglesias | Traded away | Bal | | After |
| 3/27/2012 | Bos | Lawrie | Traded away | Bal | | After |
| 3/27/2012 | Bos | Litsch | Traded away | Bal | | After |
| 3/27/2012 | Bos | Matusz | Traded away | Bal | | After |
| 3/27/2012 | Bos | May | Traded away | Bal | | After |
| 3/27/2012 | Bos | McNutt | Traded away | Bal | | After |
| 3/27/2012 | Bos | Miller | Traded away | Bal | | After |
| 3/27/2012 | Bos | Moustakas | Traded away | Bal | | After |
| 3/27/2012 | Bos | O'Sullivan | Traded away | Bal | | After |
| 3/27/2012 | Bos | Porcello | Traded away | Bal | | After |
| 3/27/2012 | Bos | Saunders | Traded away | Bal | | After |
| 3/27/2012 | Bos | Sipp | Traded away | Bal | | After |
| 3/27/2012 | Bos | Smoak | Traded away | Bal | | After |
| 3/27/2012 | Bos | Stewart | Traded away | Bal | | After |
| 3/27/2012 | Bos | Weeks | Traded away | Bal | | After |
| 3/27/2012 | Bos | Wood | Traded away | Bal | | After |
| 3/27/2012 | Bos | Zimmermann | Traded away | Bal | | After |
| 3/27/2012 | Sea | Alvarez | Traded away | SF | | After |
| 3/27/2012 | Sea | Anderson | Traded away | SF | | After |
| 3/27/2012 | Sea | Capps | Traded away | SF | | After |
| 3/27/2012 | Sea | Flowers | Traded away | SF | | After |
| 3/27/2012 | Sea | Fowler | Traded away | SF | | After |
| 3/27/2012 | Sea | Gallardo | Traded away | SF | | After |
| 3/27/2012 | Sea | Garland | Traded away | SF | | After |
| 3/27/2012 | Sea | Gwynn | Traded away | SF | | After |
| 3/27/2012 | Sea | Harden | Traded away | SF | | After |
| 3/27/2012 | Sea | Hawksworth | Traded away | SF | | After |
| 3/27/2012 | Sea | Heyward | Traded away | SF | | After |
| 3/27/2012 | Sea | Hill | Traded away | SF | | After |
| 3/27/2012 | Sea | Holland | Traded away | SF | | After |
| 3/27/2012 | Sea | Hosmer | Traded away | SF | | After |
| 3/27/2012 | Sea | Kotchman | Traded away | SF | | After |
| 3/27/2012 | Sea | Lopez | Traded away | SF | | After |
| 3/27/2012 | Sea | McLouth | Traded away | SF | | After |
| 3/27/2012 | Sea | Mitchell | Traded away | SF | | After |
| 3/27/2012 | Sea | Pacheco | Traded away | SF | | After |
| 3/27/2012 | Sea | Pena | Traded away | SF | | After |
| 3/27/2012 | Sea | Perez | Traded away | SF | | After |
| 3/27/2012 | Sea | Perez | Traded away | SF | | After |
| 3/27/2012 | Sea | Qualls | Traded away | SF | | After |
| 3/27/2012 | Sea | Rasmus | Traded away | SF | | After |
| 3/27/2012 | Sea | Rios | Traded away | SF | | After |
| 3/27/2012 | Sea | Sanchez | Traded away | SF | | After |
| 3/27/2012 | Sea | Schlereth | Traded away | SF | | After |
| 3/27/2012 | Sea | Soriano | Traded away | SF | | After |
| 3/27/2012 | Sea | Tejada | Traded away | SF | | After |
| 3/27/2012 | Sea | Thatcher | Traded away | SF | | After |
| 3/27/2012 | Sea | Theriot | Traded away | SF | | After |
| 3/27/2012 | Sea | Turner | Traded away | SF | | After |
| 3/27/2012 | Sea | Volquez | Traded away | SF | | After |
| 3/27/2012 | Sea | Wang | Traded away | SF | | After |
| 3/27/2012 | Sea | Zambrano | Traded away | SF | | After |
| 4/6/2012 | LAA | Beltre | Demoted to reserve roster | | | Before |
| 4/6/2012 | LAA | Castillo | Demoted to reserve roster | | | Before |
| 4/6/2012 | LAA | James | Demoted to reserve roster | | | Before |
| 4/6/2012 | LAA | Oramas | Demoted to reserve roster | | | Before |
| 4/6/2012 | LAA | Pimentel | Demoted to reserve roster | | | Before |
| 4/6/2012 | LAA | Villar | Demoted to reserve roster | | | Before |
| 4/6/2012 | Sea | Arcia | Released | | | Before |
| 4/8/2012 | Bal | Adrianza | Demoted to reserve roster | | | Before |
| 4/8/2012 | Bal | Anderson | Demoted to reserve roster | | | Before |
| 4/8/2012 | Bal | Clemens | Demoted to reserve roster | | | Before |
| 4/8/2012 | Bal | Hunter | Demoted to reserve roster | | | Before |
| 4/8/2012 | Bal | Iglesias | Demoted to reserve roster | | | Before |
| 4/8/2012 | Bal | O'Sullivan | Demoted to reserve roster | | | Before |
| 4/8/2012 | Bal | Stewart | Demoted to reserve roster | | | Before |
| 4/8/2012 | Tex | Daley | Demoted to reserve roster | | | Before |
| 4/9/2012 | Bos | Eaton | Promoted to active roster | | | Before |
| 4/9/2012 | Bos | Hudson | Demoted to reserve roster | | | Before |
| 4/9/2012 | Bos | Iwakuma | Promoted to active roster | | | Before |
| 4/9/2012 | Bos | Lilly | Demoted to reserve roster | | | Before |
| 4/9/2012 | Bos | Torres | Demoted to reserve roster | | | Before |
| 4/9/2012 | Bos | Wilson | Promoted to active roster | | | Before |
| 4/9/2012 | LAA | Castillo | Promoted to active roster | | | Before |
| 4/9/2012 | LAA | Lowrie | Demoted to reserve roster | | | Before |
| 4/9/2012 | Tor | Saito | Demoted to reserve roster | | | Before |
| 4/12/2012 | Cle | DeJesus | Traded away | Det | | After |
| 4/12/2012 | Cle | Happ | Acquired via trade | Det | | After |
| 4/12/2012 | Cle | Joseph | Traded away | Det | | After |
| 4/12/2012 | Det | DeJesus | Acquired via trade | Cle | | After |
| 4/12/2012 | Det | Happ | Traded away | Cle | | After |
| 4/12/2012 | Det | Joseph | Acquired via trade | Cle | | After |
| 4/12/2012 | Tam | Madson | Demoted to reserve roster | | | Before |
| 4/12/2012 | Tor | Perez | Acquired via trade | SF | | After |
| 4/12/2012 | Tor | Wilson | Traded away | SF | | After |
| 4/13/2012 | Bal | O'Sullivan | Released | | | Before |
| 4/13/2012 | Bal | Robinson | Signed | | | Before |
| 4/13/2012 | Bos | Campana | Signed | | | Before |
| 4/13/2012 | Bos | Fuentes | Promoted to active roster | | | Before |
| 4/13/2012 | Bos | Gillies | Released | | | Before |
| 4/13/2012 | Bos | Kawasaki | Released | | | Before |
| 4/13/2012 | Bos | Tateyama | Demoted to reserve roster | | | Before |
| 4/13/2012 | ChA | Kirkman | Promoted to active roster | | | Before |
| 4/13/2012 | ChA | Outman | Demoted to reserve roster | | | Before |
| 4/13/2012 | Cle | Carraway | Signed | | | Before |
| 4/13/2012 | Cle | Carrera | Signed | | | Before |
| 4/13/2012 | Cle | Robinson | Released | | | Before |
| 4/13/2012 | Det | Baker | Released | | | Before |
| 4/13/2012 | Det | Baker | Signed | | | Before |
| 4/13/2012 | Det | Cabrera | Signed | | | Before |
| 4/13/2012 | Det | Carrera | Released | | | Before |
| 4/13/2012 | Det | Castro | Released | | | Before |
| 4/13/2012 | Det | Castro | Signed | | | Before |
| 4/13/2012 | Det | Olivo | Released | | | Before |
| 4/13/2012 | Det | Olivo | Signed | | | Before |
| 4/13/2012 | KC | Balester | Demoted to reserve roster | | | Before |
| 4/13/2012 | KC | Lyon | Signed | | | Before |
| 4/13/2012 | KC | Lyon | Promoted to active roster | | | Before |
| 4/13/2012 | KC | Price | Released | | | Before |
| 4/13/2012 | Tam | Dillard | Released | | | Before |
| 4/13/2012 | Tam | Keppinger | Released | | | Before |
| 4/13/2012 | Tex | Hawkins | Signed | | | Before |
| 4/13/2012 | Tor | Fiers | Demoted to reserve roster | | | Before |
| 4/13/2012 | Tor | Francis | Promoted to active roster | | | Before |
| 4/13/2012 | Tor | Herrera | Promoted to active roster | | | Before |
| 4/17/2012 | Bal | Anderson | Promoted to active roster | | | Before |
| 4/17/2012 | Bal | Blanks | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bal | Britton | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bal | Hunter | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bal | Hunter | Promoted to active roster | | | Before |
| 4/17/2012 | Bal | Iglesias | Promoted to active roster | | | Before |
| 4/17/2012 | Bal | Litsch | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bal | Robinson | Promoted to active roster | | | Before |
| 4/17/2012 | Bal | Stewart | Promoted to active roster | | | Before |
| 4/17/2012 | Bal | Wood | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bos | Campana | Promoted to active roster | | | Before |
| 4/17/2012 | Bos | Eaton | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bos | Lilly | Promoted to active roster | | | Before |
| 4/17/2012 | Bos | Overbay | Demoted to reserve roster | | | Before |
| 4/17/2012 | Bos | Pineiro | Promoted to active roster | | | Before |
| 4/17/2012 | Bos | Wilson | Demoted to reserve roster | | | Before |
| 4/17/2012 | Tam | Amarista | Promoted to active roster | | | Before |
| 4/17/2012 | Tam | Ellsbury | Demoted to reserve roster | | | Before |
| 4/17/2012 | Tam | Mier | Promoted to active roster | | | Before |
| 4/17/2012 | Tam | Morris | Promoted to active roster | | | Before |
| 4/19/2012 | Oak | Weiland | Released | | | Before |
| 4/19/2012 | Tor | d'Arnaud | Released | | | Before |
| 4/19/2012 | Tor | Parrino | Signed | | | Before |
| 4/23/2012 | ChA | Hudson | Demoted to reserve roster | | | Before |
| 4/23/2012 | ChA | Lannan | Promoted to active roster | | | Before |
| 4/23/2012 | Det | Lin | Released | | | Before |
| 4/23/2012 | Det | Santos | Signed | | | Before |
| 4/23/2012 | KC | Berkman | Demoted to reserve roster | | | Before |
| 4/23/2012 | KC | Cowgill | Promoted to active roster | | | Before |
| 4/23/2012 | LAA | Green | Demoted to reserve roster | | | Before |
| 4/23/2012 | LAA | Lowrie | Promoted to active roster | | | Before |
| 4/23/2012 | Tor | Camp | Demoted to reserve roster | | | Before |
| 4/23/2012 | Tor | Contreras | Promoted to active roster | | | Before |
| 4/23/2012 | Tor | Fiers | Promoted to active roster | | | Before |
| 4/23/2012 | Tor | Lee | Demoted to reserve roster | | | Before |
| 4/23/2012 | Tor | Lutz | Promoted to active roster | | | Before |
| 4/23/2012 | Tor | Zuanich | Released | | | Before |
| 5/1/2012 | Bos | Eaton | Promoted to active roster | | | Before |
| 5/1/2012 | Bos | Overbay | Promoted to active roster | | | Before |
| 5/1/2012 | Bos | Pineiro | Demoted to reserve roster | | | Before |
| 5/1/2012 | Bos | Zimmerman | Demoted to reserve roster | | | Before |
| 5/1/2012 | Det | Carmona | Released | | | Before |
| 5/1/2012 | Det | Ely | Signed | | | Before |
| 5/1/2012 | Det | Galvez | Released | | | Before |
| 5/1/2012 | Det | Moore | Signed | | | Before |
| 5/1/2012 | Oak | Heckathorn | Signed | | | Before |
| 5/7/2012 | Bal | Carpenter | Signed | | | Before |
| 5/7/2012 | Bal | Hunter | Released | | | Before |
| 5/7/2012 | Bos | Eaton | Demoted to reserve roster | | | Before |
| 5/7/2012 | Bos | Fuentes | Demoted to reserve roster | | | Before |
| 5/7/2012 | Bos | Hudson | Promoted to active roster | | | Before |
| 5/7/2012 | Bos | Luebke | Demoted to reserve roster | | | Before |
| 5/7/2012 | Bos | Overbay | Demoted to reserve roster | | | Before |
| 5/7/2012 | Bos | Overbay | Promoted to active roster | | | Before |
| 5/7/2012 | Bos | Pineiro | Released | | | Before |
| 5/7/2012 | Bos | Pineiro | Signed | | | Before |
| 5/7/2012 | Bos | Tateyama | Promoted to active roster | | | Before |
| 5/7/2012 | Bos | Torres | Promoted to active roster | | | Before |
| 5/7/2012 | Bos | Wilson | Released | | | Before |
| 5/7/2012 | ChA | Johnson | Released | | | Before |
| 5/7/2012 | ChA | Martin | Demoted to reserve roster | | | Before |
| 5/7/2012 | ChA | Nieuwenhuis | Promoted to active roster | | | Before |
| 5/7/2012 | ChA | Perez | Promoted to active roster | | | Before |
| 5/7/2012 | ChA | Reimold | Demoted to reserve roster | | | Before |
| 5/7/2012 | Cle | Arrieta | Demoted to reserve roster | | | Before |
| 5/7/2012 | Cle | Carp | Promoted to active roster | | | Before |
| 5/7/2012 | KC | Valdespin | Promoted to active roster | | | Before |
| 5/7/2012 | KC | Youkilis | Demoted to reserve roster | | | Before |
| 5/7/2012 | Min | Gonzalez | Demoted to reserve roster | | | Before |
| 5/7/2012 | Min | Thome | Demoted to reserve roster | | | Before |
| 5/7/2012 | Min | Valbuena | Promoted to active roster | | | Before |
| 5/7/2012 | Min | Wuertz | Promoted to active roster | | | Before |
| 5/7/2012 | NYA | Dirks | Promoted to active roster | | | Before |
| 5/7/2012 | NYA | Rivera | Demoted to reserve roster | | | Before |
| 5/7/2012 | Sea | Ka'aihue | Promoted to active roster | | | Before |
| 5/7/2012 | Sea | Sandoval | Demoted to reserve roster | | | Before |
| 5/7/2012 | Tam | Bray | Demoted to reserve roster | | | Before |
| 5/7/2012 | Tam | Corbin | Promoted to active roster | | | Before |
| 5/7/2012 | Tam | Santos | Demoted to reserve roster | | | Before |
| 5/7/2012 | Tam | Spruill | Promoted to active roster | | | Before |
| 5/7/2012 | Tor | Chen | Promoted to active roster | | | Before |
| 5/7/2012 | Tor | Crisp | Demoted to reserve roster | | | Before |
| 5/7/2012 | Tor | Fiers | Demoted to reserve roster | | | Before |
| 5/7/2012 | Tor | Navarro | Promoted to active roster | | | Before |
| 5/8/2012 | Oak | Street | Demoted to reserve roster | | | Before |
| 5/8/2012 | Tex | Cecil | Demoted to reserve roster | | | Before |
| 5/8/2012 | Tex | Young | Demoted to reserve roster | | | Before |
| 5/10/2012 | Cle | Guthrie | Acquired via trade | Cin | | After |
| 5/10/2012 | Cle | Putnam | Traded away | Cin | | After |
| 5/10/2012 | Cle | Sanchez | Traded away | Cin | | After |
| 5/11/2012 | Cle | Arrieta | Promoted to active roster | | | Before |
| 5/11/2012 | Cle | Carrera | Promoted to active roster | | | Before |
| 5/11/2012 | Det | Santos | Released | | | Before |
| 5/11/2012 | Min | Forsythe | Signed | | | Before |
| 5/11/2012 | Min | Gonzalez | Released | | | Before |
| 5/11/2012 | Tor | Cloyd | Signed | | | Before |
| 5/14/2012 | Bal | Beckham | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Avery | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Avery | Promoted to active roster | | | Before |
| 5/14/2012 | Bos | Cutler | Signed | | | Before |
| 5/14/2012 | Bos | Cutler | Promoted to active roster | | | Before |
| 5/14/2012 | Bos | Eaton | Promoted to active roster | | | Before |
| 5/14/2012 | Bos | Fuentes | Promoted to active roster | | | Before |
| 5/14/2012 | Bos | Iannetta | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Marmol | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Nix | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Overbay | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Overbay | Promoted to active roster | | | Before |
| 5/14/2012 | Bos | Werth | Demoted to reserve roster | | | Before |
| 5/14/2012 | Bos | Zimmerman | Promoted to active roster | | | Before |
| 5/14/2012 | Cle | Carraway | Promoted to active roster | | | Before |
| 5/14/2012 | Cle | Delabar | Signed | | | Before |
| 5/14/2012 | Cle | Delabar | Promoted to active roster | | | Before |
| 5/14/2012 | Cle | Escalona | Released | | | Before |
| 5/14/2012 | Cle | Kang | Signed | | | Before |
| 5/14/2012 | Cle | Kang | Promoted to active roster | | | Before |
| 5/14/2012 | Cle | Songco | Released | | | Before |
| 5/14/2012 | Cle | Tomlin | Demoted to reserve roster | | | Before |
| 5/14/2012 | Det | Moore | Released | | | Before |
| 5/14/2012 | LAA | Green | Promoted to active roster | | | Before |
| 5/14/2012 | LAA | Rivera | Demoted to reserve roster | | | Before |
| 5/14/2012 | Min | Hairston | Demoted to reserve roster | | | Before |
| 5/14/2012 | Min | Lavarnway | Promoted to active roster | | | Before |
| 5/14/2012 | Min | Ramos | Demoted to reserve roster | | | Before |
| 5/14/2012 | Min | Saladino | Promoted to active roster | | | Before |
| 5/14/2012 | NYA | Dirks | Demoted to reserve roster | | | Before |
| 5/14/2012 | NYA | Matsui | Promoted to active roster | | | Before |
| 5/14/2012 | Sea | Blackmon | Promoted to active roster | | | Before |
| 5/14/2012 | Sea | Parker | Promoted to active roster | | | Before |
| 5/14/2012 | Sea | Thole | Demoted to reserve roster | | | Before |
| 5/14/2012 | Tor | Chen | Demoted to reserve roster | | | Before |
| 5/14/2012 | Tor | Lee | Promoted to active roster | | | Before |
| 5/18/2012 | Cle | Kang | Demoted to reserve roster | | | Before |
| 5/18/2012 | Cle | Nava | Signed | | | Before |
| 5/18/2012 | Cle | Nava | Promoted to active roster | | | Before |
| 5/18/2012 | Cle | Withrow | Released | | | Before |
| 5/18/2012 | Det | Diamond | Signed | | | Before |
| 5/18/2012 | Det | Moskos | Released | | | Before |
| 5/18/2012 | NYA | Ankiel | Signed | | | Before |
| 5/18/2012 | NYA | Vazquez | Released | | | Before |
| 5/18/2012 | Tam | Kendrick | Released | | | Before |
| 5/18/2012 | Tam | Rhymes | Signed | | | Before |
| 5/18/2012 | Tam | Varvaro | Released | | | Before |
| 5/20/2012 | Bos | Avery | Traded away | ChN | | After |
| 5/20/2012 | Bos | DeJesus | Acquired via trade | ChN | | After |
| 5/20/2012 | Bos | Snyder | Acquired via trade | ChN | | After |
| 5/21/2012 | Bos | Cutler | Released | | | Before |
| 5/21/2012 | Bos | Overbay | Demoted to reserve roster | | | Before |
| 5/21/2012 | ChA | Niemann | Demoted to reserve roster | | | Before |
| 5/21/2012 | ChA | Peralta | Promoted to active roster | | | Before |
| 5/21/2012 | KC | Bartlett | Demoted to reserve roster | | | Before |
| 5/21/2012 | KC | Berkman | Promoted to active roster | | | Before |
| 5/21/2012 | KC | Cowgill | Demoted to reserve roster | | | Before |
| 5/21/2012 | KC | Havens | Promoted to active roster | | | Before |
| 5/21/2012 | Sea | Dempster | Promoted to active roster | | | Before |
| 5/21/2012 | Sea | Webb | Promoted to active roster | | | Before |
| 5/21/2012 | Sea | Worley | Demoted to reserve roster | | | Before |
| 5/21/2012 | Tam | Rhymes | Released | | | Before |
| 5/23/2012 | LAA | Bonifacio | Demoted to reserve roster | | | Before |
| 5/23/2012 | Oak | Ellis | Demoted to reserve roster | | | Before |
| 5/23/2012 | Tex | Guyer | Demoted to reserve roster | | | Before |
| 5/23/2012 | Tex | Young | Promoted to active roster | | | Before |
| 5/25/2012 | Bos | Fuld | Signed | | | Before |
| 5/25/2012 | KC | Alderson | Signed | | | Before |
| 5/25/2012 | KC | Balester | Released | | | Before |
| 5/25/2012 | LAA | Beltre | Promoted to active roster | | | Before |
| 5/25/2012 | LAA | Fontenot | Signed | | | Before |
| 5/25/2012 | LAA | Fontenot | Promoted to active roster | | | Before |
| 5/25/2012 | LAA | Torrealba | Released | | | Before |
| 5/25/2012 | Sea | Blackmon | Demoted to reserve roster | | | Before |
| 5/25/2012 | Sea | Maldonado | Signed | | | Before |
| 5/25/2012 | Sea | Maldonado | Promoted to active roster | | | Before |
| 5/25/2012 | Sea | Villanueva | Demoted to reserve roster | | | Before |
| 5/28/2012 | Bos | Fuld | Released | | | Before |
| 5/28/2012 | ChA | Danks | Demoted to reserve roster | | | Before |
| 5/28/2012 | ChA | McPherson | Promoted to active roster | | | Before |
| 5/28/2012 | Cle | Darnell | Demoted to reserve roster | | | Before |
| 5/28/2012 | Cle | Guthrie | Promoted to active roster | | | Before |
| 5/28/2012 | Cle | Kang | Promoted to active roster | | | Before |
| 5/28/2012 | Cle | Sellers | Demoted to reserve roster | | | Before |
| 5/28/2012 | LAA | Castillo | Demoted to reserve roster | | | Before |
| 5/28/2012 | Min | Blackburn | Demoted to reserve roster | | | Before |
| 5/28/2012 | Min | Hairston | Promoted to active roster | | | Before |
| 5/28/2012 | NYA | Dirks | Demoted to reserve roster | | | Before |
| 5/28/2012 | NYA | Dirks | Promoted to active roster | | | Before |
| 5/28/2012 | NYA | Feliz | Demoted to reserve roster | | | Before |
| 5/28/2012 | NYA | McAllister | Promoted to active roster | | | Before |
| 5/28/2012 | Oak | Heckathorn | Released | | | Before |
| 5/28/2012 | Oak | McCarthy | Demoted to reserve roster | | | Before |
| 5/28/2012 | Oak | Miller | Signed | | | Before |
| 5/28/2012 | Oak | Miller | Promoted to active roster | | | Before |
| 5/28/2012 | Oak | Ross | Demoted to reserve roster | | | Before |
| 5/28/2012 | Oak | Vogelsong | Promoted to active roster | | | Before |
| 5/28/2012 | Tor | Crisp | Promoted to active roster | | | Before |
| 5/28/2012 | Tor | Jones | Signed | | | Before |
| 5/28/2012 | Tor | Lutz | Demoted to reserve roster | | | Before |
| 5/28/2012 | Tor | Parrino | Released | | | Before |
| 5/29/2012 | KC | Berkman | Demoted to reserve roster | | | Before |
| 5/29/2012 | KC | Wells | Demoted to reserve roster | | | Before |
| 5/29/2012 | KC | Youkilis | Promoted to active roster | | | Before |
| 5/31/2012 | NYA | Aceves | Acquired via trade | Cin | | After |
| 5/31/2012 | NYA | Nova | Traded away | Cin | | After |
| 6/1/2012 | Bos | Heathcott | Signed | | | Before |
| 6/1/2012 | Bos | Meadows | Signed | | | Before |
| 6/1/2012 | Bos | Pineiro | Released | | | Before |
| 6/1/2012 | Cle | Hunter | Signed | | | Before |
| 6/1/2012 | Cle | Hunter | Promoted to active roster | | | Before |
| 6/1/2012 | Cle | Kang | Released | | | Before |
| 6/1/2012 | Cle | Sellers | Released | | | Before |
| 6/1/2012 | KC | Jackson | Demoted to reserve roster | | | Before |
| 6/1/2012 | Oak | Blanco | Signed | | | Before |
| 6/1/2012 | Tex | Hawkins | Demoted to reserve roster | | | Before |
| 6/1/2012 | Tex | Villarreal | Signed | | | Before |
| 6/2/2012 | ChA | Arcia | Signed | | | Before |
| 6/2/2012 | KC | Colon | Signed | | | Before |
| 6/4/2012 | Bos | Eaton | Demoted to reserve roster | | | Before |
| 6/4/2012 | Bos | Lilly | Demoted to reserve roster | | | Before |
| 6/4/2012 | Bos | Marmol | Promoted to active roster | | | Before |
| 6/4/2012 | Bos | Meadows | Promoted to active roster | | | Before |
| 6/4/2012 | ChA | Arcia | Promoted to active roster | | | Before |
| 6/4/2012 | ChA | Jay | Demoted to reserve roster | | | Before |
| 6/4/2012 | ChA | Quentin | Promoted to active roster | | | Before |
| 6/4/2012 | ChA | Schierholtz | Demoted to reserve roster | | | Before |
| 6/4/2012 | Cle | Arrieta | Demoted to reserve roster | | | Before |
| 6/4/2012 | Cle | Tomlin | Promoted to active roster | | | Before |
| 6/4/2012 | KC | Clevenger | Promoted to active roster | | | Before |
| 6/4/2012 | KC | Cowgill | Promoted to active roster | | | Before |
| 6/4/2012 | KC | Snider | Demoted to reserve roster | | | Before |
| 6/4/2012 | NYA | Ankiel | Released | | | Before |
| 6/4/2012 | NYA | Halladay | Demoted to reserve roster | | | Before |
| 6/4/2012 | NYA | Hechavarria | Promoted to active roster | | | Before |
| 6/4/2012 | NYA | Nunez | Demoted to reserve roster | | | Before |
| 6/4/2012 | NYA | Reifer | Promoted to active roster | | | Before |
| 6/4/2012 | Sea | Thole | Promoted to active roster | | | Before |
| 6/4/2012 | Tam | Cooper | Promoted to active roster | | | Before |
| 6/4/2012 | Tam | Miller | Promoted to active roster | | | Before |
| 6/4/2012 | Tam | Weaver | Demoted to reserve roster | | | Before |
| 6/4/2012 | Tor | Branyan | Promoted to active roster | | | Before |
| 6/4/2012 | Tor | Contreras | Demoted to reserve roster | | | Before |
| 6/4/2012 | Tor | Fiers | Promoted to active roster | | | Before |
| 6/7/2012 | Bos | Campana | Traded away | ChN | | After |
| 6/7/2012 | Bos | Davis | Acquired via trade | ChN | | After |
| 6/7/2012 | Bos | Eaton | Traded away | ChN | | After |
| 6/7/2012 | ChA | Outman | Promoted to active roster | | | Before |
| 6/8/2012 | Bos | Galvez | Signed | | | Before |
| 6/8/2012 | Bos | Meadows | Released | | | Before |
| 6/8/2012 | Bos | Moore | Signed | | | Before |
| 6/8/2012 | Bos | Moore | Promoted to active roster | | | Before |
| 6/8/2012 | ChA | Hudson | Promoted to active roster | | | Before |
| 6/8/2012 | ChA | Lannan | Demoted to reserve roster | | | Before |
| 6/8/2012 | ChA | Mazzaro | Signed | | | Before |
| 6/8/2012 | ChA | Mazzaro | Demoted to reserve roster | | | Before |
| 6/8/2012 | ChA | Mazzaro | Promoted to active roster | | | Before |
| 6/8/2012 | ChA | McPherson | Demoted to reserve roster | | | Before |
| 6/8/2012 | Tor | Emaus | Demoted to reserve roster | | | Before |
| 6/9/2012 | Tex | Oswalt | Promoted to active roster | | | Before |
| 6/11/2012 | Bos | Galvez | Released | | | Before |
| 6/11/2012 | Bos | McDonald | Signed | | | Before |
| 6/11/2012 | Bos | McDonald | Promoted to active roster | | | Before |
| 6/11/2012 | Bos | Moore | Released | | | Before |
| 6/11/2012 | ChA | Moskos | Signed | | | Before |
| 6/11/2012 | ChA | Tejeda | Released | | | Before |
| 6/11/2012 | Cle | Arrieta | Promoted to active roster | | | Before |
| 6/11/2012 | Cle | Carignan | Demoted to reserve roster | | | Before |
| 6/11/2012 | Det | Beavan | Promoted to active roster | | | Before |
| 6/11/2012 | Det | Cabrera | Released | | | Before |
| 6/11/2012 | Det | DeJesus | Demoted to reserve roster | | | Before |
| 6/11/2012 | LAA | Beltre | Demoted to reserve roster | | | Before |
| 6/11/2012 | LAA | Beltre | Promoted to active roster | | | Before |
| 6/11/2012 | LAA | Rivera | Promoted to active roster | | | Before |
| 6/11/2012 | Oak | Blanco | Promoted to active roster | | | Before |
| 6/11/2012 | Oak | Cook | Demoted to reserve roster | | | Before |
| 6/11/2012 | Oak | McCarthy | Promoted to active roster | | | Before |
| 6/11/2012 | Oak | Street | Promoted to active roster | | | Before |
| 6/11/2012 | Sea | Garcia | Demoted to reserve roster | | | Before |
| 6/11/2012 | Sea | Guerra | Demoted to reserve roster | | | Before |
| 6/11/2012 | Sea | Sandoval | Promoted to active roster | | | Before |
| 6/11/2012 | Sea | Worley | Promoted to active roster | | | Before |
| 6/14/2012 | Bal | Pineda | Acquired via trade | Det | | After |
| 6/14/2012 | Bal | Zimmermann | Traded away | Det | | After |
| 6/14/2012 | ChA | Gregerson | Acquired via trade | Pit | | After |
| 6/14/2012 | ChA | Motte | Traded away | Pit | | After |
| 6/14/2012 | Cle | Arrieta | Traded away | SF | | After |
| 6/14/2012 | Cle | Capps | Acquired via trade | SF | | After |
| 6/14/2012 | Cle | Darnell | Traded away | Was | | After |
| 6/14/2012 | Cle | Hafner | Acquired via trade | Was | | After |
| 6/14/2012 | Cle | Hill | Acquired via trade | SF | | After |
| 6/14/2012 | Cle | Rios | Acquired via trade | SF | | After |
| 6/14/2012 | Cle | Soriano | Acquired via trade | SF | | After |
| 6/14/2012 | Cle | Thatcher | Acquired via trade | SF | | After |
| 6/14/2012 | Cle | Zambrano | Acquired via trade | SF | | After |
| 6/14/2012 | Det | Bard | Traded away | Pit | | After |
| 6/14/2012 | Det | Beavan | Traded away | Pit | | After |
| 6/14/2012 | Det | Burns | Acquired via trade | Hou | | After |
| 6/14/2012 | Det | Davis | Traded away | Hou | | After |
| 6/14/2012 | Det | Desmond | Acquired via trade | Pit | | After |
| 6/14/2012 | Det | Detwiler | Acquired via trade | Hou | | After |
| 6/14/2012 | Det | Gordon | Acquired via trade | Pit | | After |
| 6/14/2012 | Det | Hamels | Acquired via trade | Pit | | After |
| 6/14/2012 | Det | Kemp | Traded away | Pit | | After |
| 6/14/2012 | Det | Pineda | Traded away | Bal | | After |
| 6/14/2012 | Det | Swagerty | Traded away | Pit | | After |
| 6/14/2012 | Det | Zimmermann | Acquired via trade | Bal | | After |
| 6/15/2012 | ChA | Giavotella | Demoted to reserve roster | | | Before |
| 6/15/2012 | ChA | Lillibridge | Signed | | | Before |
| 6/15/2012 | ChA | Lillibridge | Promoted to active roster | | | Before |
| 6/15/2012 | ChA | Mazzaro | Promoted to active roster | | | Before |
| 6/15/2012 | ChA | Outman | Demoted to reserve roster | | | Before |
| 6/15/2012 | ChA | Schierholtz | Released | | | Before |
| 6/15/2012 | Cle | Brown | Demoted to reserve roster | | | Before |
| 6/15/2012 | Cle | Brown | Promoted to active roster | | | Before |
| 6/15/2012 | Cle | Carignan | Released | | | Before |
| 6/15/2012 | Cle | Carraway | Demoted to reserve roster | | | Before |
| 6/15/2012 | Cle | Carrera | Released | | | Before |
| 6/15/2012 | Cle | Carter | Demoted to reserve roster | | | Before |
| 6/15/2012 | Cle | Delabar | Demoted to reserve roster | | | Before |
| 6/15/2012 | Cle | Gomez | Demoted to reserve roster | | | Before |
| 6/15/2012 | Det | Arroyo | Demoted to reserve roster | | | Before |
| 6/15/2012 | Det | Burns | Promoted to active roster | | | Before |
| 6/15/2012 | Det | de los Santos | Demoted to reserve roster | | | Before |
| 6/15/2012 | Det | Detwiler | Promoted to active roster | | | Before |
| 6/15/2012 | Det | Liddi | Demoted to reserve roster | | | Before |
| 6/17/2012 | Cle | Burns | Acquired via trade | Det | | After |
| 6/17/2012 | Cle | Gearrin | Acquired via trade | Det | | After |
| 6/17/2012 | Det | Burns | Traded away | Cle | | After |
| 6/17/2012 | Det | Gearrin | Traded away | Cle | | After |
| 6/18/2012 | Cle | Carp | Demoted to reserve roster | | | Before |
| 6/18/2012 | Cle | Gearrin | Promoted to active roster | | | Before |
| 6/18/2012 | Cle | Moscoso | Demoted to reserve roster | | | Before |
| 6/18/2012 | Det | Mijares | Signed | | | Before |
| 6/18/2012 | Det | Mijares | Promoted to active roster | | | Before |
| 6/18/2012 | KC | Carreno | Promoted to active roster | | | Before |
| 6/18/2012 | KC | Havens | Demoted to reserve roster | | | Before |
| 6/18/2012 | KC | Morrow | Demoted to reserve roster | | | Before |
| 6/18/2012 | KC | Roberts | Promoted to active roster | | | Before |
| 6/18/2012 | KC | Snider | Promoted to active roster | | | Before |
| 6/18/2012 | Sea | Parker | Demoted to reserve roster | | | Before |
| 6/18/2012 | Sea | Scott | Demoted to reserve roster | | | Before |
| 6/18/2012 | Sea | Villanueva | Promoted to active roster | | | Before |
| 6/18/2012 | Tam | Amarista | Demoted to reserve roster | | | Before |
| 6/18/2012 | Tam | Castro | Demoted to reserve roster | | | Before |
| 6/18/2012 | Tam | Matsuzaka | Promoted to active roster | | | Before |
| 6/18/2012 | Tam | Melville | Promoted to active roster | | | Before |
| 6/18/2012 | Tam | Mier | Demoted to reserve roster | | | Before |
| 6/18/2012 | Tam | Mier | Promoted to active roster | | | Before |
| 6/18/2012 | Tex | Beckett | Demoted to reserve roster | | | Before |
| 6/18/2012 | Tex | Cecil | Promoted to active roster | | | Before |
| 6/18/2012 | Tex | Ogando | Demoted to reserve roster | | | Before |
| 6/18/2012 | Tex | Schoop | Promoted to active roster | | | Before |
| 6/18/2012 | Tex | Villarreal | Demoted to reserve roster | | | Before |
| 6/18/2012 | Tex | Villarreal | Promoted to active roster | | | Before |
| 6/21/2012 | Bos | Carroll | Acquired via trade | Phi | | After |
| 6/21/2012 | Bos | Scutaro | Traded away | Cle | | After |
| 6/21/2012 | Cle | Scutaro | Acquired via trade | Bos | | After |
| 6/22/2012 | Bal | Carpenter | Released | | | Before |
| 6/22/2012 | Bal | Kendrick | Signed | | | Before |
| 6/22/2012 | Cle | Hunter | Demoted to reserve roster | | | Before |
| 6/22/2012 | Cle | Moscoso | Released | | | Before |
| 6/22/2012 | KC | Jones | Signed | | | Before |
| 6/22/2012 | Tam | James | Signed | | | Before |
| 6/22/2012 | Tam | Rice | Released | | | Before |
| 6/24/2012 | KC | Roberts | Traded away | Oak | | After |
| 6/24/2012 | Oak | Roberts | Acquired via trade | KC | | After |
| 6/25/2012 | Bos | Brach | Signed | | | Before |
| 6/25/2012 | Cle | Carter | Promoted to active roster | | | Before |
| 6/25/2012 | Cle | Moreland | Demoted to reserve roster | | | Before |
| 6/25/2012 | Det | Arroyo | Promoted to active roster | | | Before |
| 6/25/2012 | Det | Carpenter | Promoted to active roster | | | Before |
| 6/25/2012 | Det | de los Santos | Promoted to active roster | | | Before |
| 6/25/2012 | Det | Gillespie | Signed | | | Before |
| 6/25/2012 | Det | Gillespie | Promoted to active roster | | | Before |
| 6/25/2012 | Det | Hellickson | Demoted to reserve roster | | | Before |
| 6/25/2012 | Det | Mijares | Released | | | Before |
| 6/25/2012 | Det | Saunders | Demoted to reserve roster | | | Before |
| 6/25/2012 | Det | Schafer | Demoted to reserve roster | | | Before |
| 6/25/2012 | KC | Cowgill | Demoted to reserve roster | | | Before |
| 6/25/2012 | KC | Havens | Promoted to active roster | | | Before |
| 6/25/2012 | KC | Jones | Promoted to active roster | | | Before |
| 6/25/2012 | Min | Bowden | Demoted to reserve roster | | | Before |
| 6/25/2012 | Min | Forsythe | Promoted to active roster | | | Before |
| 6/25/2012 | Min | Gonzalez | Promoted to active roster | | | Before |
| 6/25/2012 | Min | Saladino | Demoted to reserve roster | | | Before |
| 6/25/2012 | Min | Slama | Demoted to reserve roster | | | Before |
| 6/25/2012 | Min | Thome | Promoted to active roster | | | Before |
| 6/25/2012 | NYA | Brackman | Released | | | Before |
| 6/25/2012 | NYA | Matsui | Released | | | Before |
| 6/25/2012 | NYA | Reifer | Released | | | Before |
| 6/25/2012 | Oak | Blanco | Demoted to reserve roster | | | Before |
| 6/25/2012 | Oak | Bogusevic | Demoted to reserve roster | | | Before |
| 6/25/2012 | Oak | Ross | Promoted to active roster | | | Before |
| 6/25/2012 | Oak | Vogelsong | Demoted to reserve roster | | | Before |
| 6/25/2012 | Oak | Vogelsong | Promoted to active roster | | | Before |
| 6/25/2012 | Sea | Ka'aihue | Released | | | Before |
| 6/25/2012 | Sea | Mijares | Signed | | | Before |
| 6/25/2012 | Tex | Daley | Released | | | Before |
| 6/25/2012 | Tex | Hawkins | Released | | | Before |
| 6/27/2012 | Oak | Marcum | Demoted to reserve roster | | | Before |
| 6/28/2012 | Bal | Gose | Traded away | SF | | After |
| 6/28/2012 | Bal | Lawrie | Traded away | SF | | After |
| 6/28/2012 | Bal | Rasmus | Acquired via trade | SF | | After |
| 6/28/2012 | Bal | Weeks | Traded away | SF | | After |
| 6/28/2012 | NYA | Banuelos | Traded away | SF | | After |
| 6/28/2012 | NYA | Hechavarria | Traded away | SF | | After |
| 6/28/2012 | NYA | Holland | Acquired via trade | SF | | After |
| 6/28/2012 | NYA | Lindblom | Traded away | Cin | | After |
| 6/29/2012 | LAA | Rodriguez | Demoted to reserve roster | | | Before |
| 6/29/2012 | NYA | Sierra | Signed | | | Before |
| 6/29/2012 | Oak | Gaudin | Signed | | | Before |
| 6/29/2012 | Tor | Camp | Promoted to active roster | | | Before |
| 6/29/2012 | Tor | Uehara | Demoted to reserve roster | | | Before |
| 7/1/2012 | ChA | Jay | Traded away | ChN | | After |
| 7/1/2012 | ChA | Lynn | Acquired via trade | ChN | | After |
| 7/1/2012 | Min | Swagerty | Acquired via trade | Pit | | After |
| 7/1/2012 | Min | Thome | Traded away | Pit | | After |
| 7/2/2012 | Bal | Cleto | Signed | | | Before |
| 7/2/2012 | ChA | Hester | Signed | | | Before |
| 7/2/2012 | ChA | Hester | Promoted to active roster | | | Before |
| 7/2/2012 | ChA | Hudson | Demoted to reserve roster | | | Before |
| 7/2/2012 | ChA | Mazzaro | Demoted to reserve roster | | | Before |
| 7/2/2012 | ChA | Molina | Released | | | Before |
| 7/2/2012 | ChA | Outman | Promoted to active roster | | | Before |
| 7/2/2012 | Det | Diamond | Promoted to active roster | | | Before |
| 7/2/2012 | Det | Mujica | Demoted to reserve roster | | | Before |
| 7/2/2012 | KC | Havens | Demoted to reserve roster | | | Before |
| 7/2/2012 | KC | Jackson | Promoted to active roster | | | Before |
| 7/2/2012 | NYA | Sabathia | Demoted to reserve roster | | | Before |
| 7/2/2012 | NYA | Sierra | Promoted to active roster | | | Before |
| 7/2/2012 | Oak | Ross | Released | | | Before |
| 7/2/2012 | Sea | Dempster | Demoted to reserve roster | | | Before |
| 7/2/2012 | Sea | Gee | Promoted to active roster | | | Before |
| 7/2/2012 | Sea | Mijares | Promoted to active roster | | | Before |
| 7/2/2012 | Tex | Beckett | Promoted to active roster | | | Before |
| 7/2/2012 | Tex | Guyer | Released | | | Before |
| 7/2/2012 | Tex | Hampson | Signed | | | Before |
| 7/2/2012 | Tex | Torrealba | Signed | | | Before |
| 7/2/2012 | Tex | Utley | Promoted to active roster | | | Before |
| 7/3/2012 | NYA | Runzler | Promoted to active roster | | | Before |
| 7/3/2012 | NYA | Runzler | Promoted to active roster | | | Before |
| 7/3/2012 | Oak | McCarthy | Demoted to reserve roster | | | Before |
| 7/4/2012 | Oak | Gaudin | Promoted to active roster | | | Before |
| 7/5/2012 | Det | Bogusevic | Acquired via trade | Oak | | After |
| 7/5/2012 | Det | de los Santos | Traded away | Oak | | After |
| 7/5/2012 | Det | Hoover | Acquired via trade | Oak | | After |
| 7/5/2012 | Oak | Bogusevic | Traded away | Det | | After |
| 7/5/2012 | Oak | de los Santos | Acquired via trade | Det | | After |
| 7/5/2012 | Oak | Hoover | Traded away | Det | | After |
| 7/6/2012 | Bos | Fuld | Signed | | | Before |
| 7/6/2012 | Bos | McDonald | Released | | | Before |
| 7/6/2012 | Cle | Carter | Demoted to reserve roster | | | Before |
| 7/6/2012 | Cle | Hafner | Promoted to active roster | | | Before |
| 7/6/2012 | KC | Jones | Released | | | Before |
| 7/6/2012 | Oak | Moss | Signed | | | Before |
| 7/6/2012 | Tor | Contreras | Released | | | Before |
| 7/6/2012 | Tor | Emaus | Released | | | Before |
| 7/8/2012 | Cle | Brown | Traded away | Sea | | After |
| 7/8/2012 | Cle | Castellanos | Traded away | Sea | | After |
| 7/8/2012 | Cle | Jackson | Acquired via trade | Sea | | After |
| 7/8/2012 | Cle | Konerko | Acquired via trade | Sea | | After |
| 7/8/2012 | Cle | Moreland | Traded away | Sea | | After |
| 7/8/2012 | Cle | Parker | Acquired via trade | Sea | | After |
| 7/8/2012 | Cle | Ramirez | Traded away | Sea | | After |
| 7/8/2012 | Det | Alburquerque | Acquired via trade | Was | | After |
| 7/8/2012 | Det | Liddi | Traded away | Was | | After |
| 7/8/2012 | KC | Frasor | Traded away | LAN | | After |
| 7/8/2012 | KC | Lombardozzi | Acquired via trade | LAN | | After |
| 7/8/2012 | KC | Rodriguez | Traded away | LAN | | After |
| 7/8/2012 | KC | Thornburg | Acquired via trade | LAN | | After |
| 7/8/2012 | Sea | Brown | Acquired via trade | Cle | | After |
| 7/8/2012 | Sea | Castellanos | Acquired via trade | Cle | | After |
| 7/8/2012 | Sea | Jackson | Traded away | Cle | | After |
| 7/8/2012 | Sea | Konerko | Traded away | Cle | | After |
| 7/8/2012 | Sea | Moreland | Acquired via trade | Cle | | After |
| 7/8/2012 | Sea | Parker | Traded away | Cle | | After |
| 7/8/2012 | Sea | Ramirez | Acquired via trade | Cle | | After |
| 7/13/2012 | Bos | Brach | Promoted to active roster | | | Before |
| 7/13/2012 | Bos | Overbay | Promoted to active roster | | | Before |
| 7/13/2012 | Bos | Venters | Demoted to reserve roster | | | Before |
| 7/13/2012 | ChA | Hester | Released | | | Before |
| 7/13/2012 | ChA | Torrealba | Signed | | | Before |
| 7/13/2012 | Cle | Hyatt | Demoted to reserve roster | | | Before |
| 7/13/2012 | Det | Desmond | Demoted to reserve roster | | | Before |
| 7/13/2012 | Det | Diamond | Demoted to reserve roster | | | Before |
| 7/13/2012 | Det | Diamond | Promoted to active roster | | | Before |
| 7/13/2012 | Det | Hellickson | Promoted to active roster | | | Before |
| 7/13/2012 | Min | DeVries | Signed | | | Before |
| 7/13/2012 | NYA | Holland | Promoted to active roster | | | Before |
| 7/13/2012 | Sea | Gee | Demoted to reserve roster | | | Before |
| 7/13/2012 | Sea | Guerra | Demoted to reserve roster | | | Before |
| 7/13/2012 | Sea | Guerra | Promoted to active roster | | | Before |
| 7/13/2012 | Sea | Guerra | Promoted to active roster | | | Before |
| 7/13/2012 | Sea | Scott | Promoted to active roster | | | Before |
| 7/13/2012 | Tex | Hawkins | Signed | | | Before |
| 7/13/2012 | Tex | Hawkins | Promoted to active roster | | | Before |
| 7/13/2012 | Tex | Rogers | Signed | | | Before |
| 7/13/2012 | Tex | Schoop | Demoted to reserve roster | | | Before |
| 7/13/2012 | Tex | Torrealba | Released | | | Before |
| 7/13/2012 | Tex | Villarreal | Demoted to reserve roster | | | Before |
| 7/13/2012 | Tex | White | Demoted to reserve roster | | | Before |
| 7/15/2012 | Tex | Arenado | Traded away | Phi | | After |
| 7/15/2012 | Tex | Jennings | Acquired via trade | Phi | | After |
| 7/16/2012 | ChA | Arcia | Demoted to reserve roster | | | Before |
| 7/16/2012 | ChA | Lannan | Promoted to active roster | | | Before |
| 7/16/2012 | ChA | Martin | Promoted to active roster | | | Before |
| 7/16/2012 | ChA | Peralta | Demoted to reserve roster | | | Before |
| 7/16/2012 | ChA | Torrealba | Promoted to active roster | | | Before |
| 7/16/2012 | KC | Seaton | Signed | | | Before |
| 7/16/2012 | LAA | Beltre | Demoted to reserve roster | | | Before |
| 7/16/2012 | LAA | Bonifacio | Promoted to active roster | | | Before |
| 7/16/2012 | LAA | Castillo | Promoted to active roster | | | Before |
| 7/16/2012 | LAA | Lowrie | Demoted to reserve roster | | | Before |
| 7/16/2012 | LAA | Rodriguez | Promoted to active roster | | | Before |
| 7/16/2012 | NYA | Helton | Demoted to reserve roster | | | Before |
| 7/16/2012 | NYA | Hembree | Demoted to reserve roster | | | Before |
| 7/16/2012 | NYA | Sanchez | Promoted to active roster | | | Before |
| 7/16/2012 | Oak | Blanco | Promoted to active roster | | | Before |
| 7/16/2012 | Oak | Cook | Promoted to active roster | | | Before |
| 7/16/2012 | Oak | Ellis | Promoted to active roster | | | Before |
| 7/16/2012 | Oak | Roberts | Demoted to reserve roster | | | Before |
| 7/16/2012 | Oak | Stanton | Demoted to reserve roster | | | Before |
| 7/16/2012 | Tam | Amarista | Promoted to active roster | | | Before |
| 7/16/2012 | Tam | Castro | Promoted to active roster | | | Before |
| 7/16/2012 | Tam | Floyd | Demoted to reserve roster | | | Before |
| 7/16/2012 | Tam | Matsuzaka | Demoted to reserve roster | | | Before |
| 7/16/2012 | Tam | Votto | Demoted to reserve roster | | | Before |
| 7/16/2012 | Tam | Weaver | Promoted to active roster | | | Before |
| 7/19/2012 | Bos | Bard | Acquired via trade | Pit | | After |
| 7/19/2012 | Det | Damon | Traded away | NYA | | After |
| 7/19/2012 | Det | Valle | Acquired via trade | NYA | | After |
| 7/19/2012 | KC | Buchholz | Acquired via trade | Was | | After |
| 7/19/2012 | KC | Casilla | Acquired via trade | Was | | After |
| 7/19/2012 | KC | Liddi | Acquired via trade | Was | | After |
| 7/19/2012 | KC | Snider | Traded away | Was | | After |
| 7/19/2012 | KC | Youkilis | Traded away | Was | | After |
| 7/19/2012 | LAA | Chisenhall | Acquired via trade | Phi | | After |
| 7/19/2012 | LAA | Lowrie | Traded away | Phi | | After |
| 7/19/2012 | NYA | Damon | Acquired via trade | Det | | After |
| 7/19/2012 | NYA | Valle | Traded away | Det | | After |
| 7/19/2012 | Sea | Wolf | Traded away | Pit | | After |
| 7/20/2012 | Bos | Tateyama | Demoted to reserve roster | | | Before |
| 7/20/2012 | Det | Arroyo | Demoted to reserve roster | | | Before |
| 7/20/2012 | Det | Bogusevic | Promoted to active roster | | | Before |
| 7/20/2012 | Det | Saunders | Promoted to active roster | | | Before |
| 7/20/2012 | Det | Valle | Demoted to reserve roster | | | Before |
| 7/20/2012 | Sea | Garate | Released | | | Before |
| 7/20/2012 | Tor | Lutz | Demoted to reserve roster | | | Before |
| 7/20/2012 | Tor | Lutz | Promoted to active roster | | | Before |
| 7/22/2012 | NYA | Betancourt | Acquired via trade | Sea | | After |
| 7/22/2012 | NYA | McAllister | Traded away | Sea | | After |
| 7/22/2012 | Sea | Betancourt | Traded away | NYA | | After |
| 7/22/2012 | Sea | McAllister | Acquired via trade | NYA | | After |
| 7/23/2012 | Bos | Ortiz | Demoted to reserve roster | | | Before |
| 7/23/2012 | Bos | Venters | Promoted to active roster | | | Before |
| 7/23/2012 | Det | Ely | Demoted to reserve roster | | | Before |
| 7/23/2012 | Det | Mujica | Promoted to active roster | | | Before |
| 7/23/2012 | KC | Berkman | Promoted to active roster | | | Before |
| 7/23/2012 | KC | Buchholz | Promoted to active roster | | | Before |
| 7/23/2012 | KC | Cowgill | Promoted to active roster | | | Before |
| 7/23/2012 | KC | Liddi | Promoted to active roster | | | Before |
| 7/23/2012 | KC | Ohman | Released | | | Before |
| 7/23/2012 | KC | Pennington | Demoted to reserve roster | | | Before |
| 7/23/2012 | KC | Seaton | Promoted to active roster | | | Before |
| 7/23/2012 | NYA | Halladay | Promoted to active roster | | | Before |
| 7/23/2012 | NYA | Sabathia | Promoted to active roster | | | Before |
| 7/23/2012 | Oak | Pina | Signed | | | Before |
| 7/23/2012 | Oak | Pina | Promoted to active roster | | | Before |
| 7/23/2012 | Oak | Sanchez | Demoted to reserve roster | | | Before |
| 7/23/2012 | Oak | Tekotte | Released | | | Before |
| 7/23/2012 | Sea | Marinez | Promoted to active roster | | | Before |
| 7/26/2012 | Bos | Reynolds | Demoted to reserve roster | | | Before |
| 7/26/2012 | Bos | Meek | Acquired via trade | Mil | | After |
| 7/26/2012 | Bos | Victorino | Acquired via trade | Mil | | After |
| 7/26/2012 | Cle | Parker | Released | | | Before |
| 7/26/2012 | Cle | Francisco | Acquired via trade | Pit | | After |
| 7/26/2012 | Tor | Herrera | Demoted to reserve roster | | | Before |
| 7/26/2012 | Tor | Saito | Promoted to active roster | | | Before |
| 7/29/2012 | NYA | Alvarez | Acquired via trade | SF | | After |
| 7/29/2012 | NYA | Feliz | Traded away | SF | | After |
| 7/30/2012 | Bos | Cust | Demoted to reserve roster | | | Before |
| 7/30/2012 | Bos | Fuld | Promoted to active roster | | | Before |
| 7/30/2012 | Bos | Iannetta | Promoted to active roster | | | Before |
| 7/30/2012 | Bos | Marson | Demoted to reserve roster | | | Before |
| 7/30/2012 | Bos | Meek | Released | | | Before |
| 7/30/2012 | Bos | Nix | Promoted to active roster | | | Before |
| 7/30/2012 | Bos | Overbay | Demoted to reserve roster | | | Before |
| 7/30/2012 | ChA | Reimold | Released | | | Before |
| 7/30/2012 | ChA | Rogers | Signed | | | Before |
| 7/30/2012 | Cle | Capps | Demoted to reserve roster | | | Before |
| 7/30/2012 | Cle | Carp | Promoted to active roster | | | Before |
| 7/30/2012 | Det | Aybar | Demoted to reserve roster | | | Before |
| 7/30/2012 | Det | Bogusevic | Demoted to reserve roster | | | Before |
| 7/30/2012 | Det | DeJesus | Promoted to active roster | | | Before |
| 7/30/2012 | Det | Schafer | Promoted to active roster | | | Before |
| 7/30/2012 | LAA | Maine | Released | | | Before |
| 7/30/2012 | LAA | Perez | Signed | | | Before |
| 7/30/2012 | NYA | Helton | Promoted to active roster | | | Before |
| 7/30/2012 | NYA | Nunez | Promoted to active roster | | | Before |
| 7/30/2012 | NYA | Rodriguez | Demoted to reserve roster | | | Before |
| 7/30/2012 | NYA | Sierra | Demoted to reserve roster | | | Before |
| 7/30/2012 | Sea | Blackmon | Promoted to active roster | | | Before |
| 7/30/2012 | Sea | Moreland | Demoted to reserve roster | | | Before |
| 7/30/2012 | Sea | Moreland | Promoted to active roster | | | Before |
| 7/30/2012 | Sea | Sandoval | Demoted to reserve roster | | | Before |
| 7/30/2012 | Tor | Hermida | Released | | | Before |
| 7/30/2012 | Tor | Lee | Released | | | Before |
| 7/31/2012 | KC | Arencibia | Demoted to reserve roster | | | Before |
| 7/31/2012 | KC | Plouffe | Demoted to reserve roster | | | Before |
| 7/31/2012 | KC | Wells | Promoted to active roster | | | Before |
| 8/2/2012 | Cle | Berkman | Acquired via trade | KC | | After |
| 8/2/2012 | Cle | Rolen | Acquired via trade | Hou | | After |
| 8/2/2012 | KC | Berkman | Traded away | Cle | | After |
| 8/2/2012 | KC | Gose | Acquired via trade | SF | | After |
| 8/2/2012 | KC | Parra | Traded away | SF | | After |
| 8/2/2012 | Oak | Giambi | Demoted to reserve roster | | | Before |
| 8/3/2012 | Cle | Carp | Demoted to reserve roster | | | Before |
| 8/3/2012 | Cle | Francisco | Promoted to active roster | | | Before |
| 8/3/2012 | Cle | Nava | Demoted to reserve roster | | | Before |
| 8/3/2012 | Cle | Reimold | Signed | | | Before |
| 8/3/2012 | Cle | Sogard | Demoted to reserve roster | | | Before |
| 8/3/2012 | KC | Guerra | Released | | | Before |
| 8/3/2012 | Min | Moylan | Signed | | | Before |
| 8/3/2012 | Min | Wuertz | Demoted to reserve roster | | | Before |
| 8/3/2012 | Tor | Branyan | Demoted to reserve roster | | | Before |
| 8/5/2012 | Cle | Francisco | Demoted to reserve roster | | | Before |
| 8/5/2012 | KC | Gose | Promoted to active roster | | | Before |
| 8/6/2012 | Bos | Evans | Signed | | | Before |
| 8/6/2012 | Bos | Nix | Released | | | Before |
| 8/6/2012 | Bos | Overbay | Released | | | Before |
| 8/6/2012 | Bos | Werth | Promoted to active roster | | | Before |
| 8/6/2012 | Cle | Berkman | Demoted to reserve roster | | | Before |
| 8/6/2012 | Cle | Carp | Promoted to active roster | | | Before |
| 8/6/2012 | Cle | Carter | Demoted to reserve roster | | | Before |
| 8/6/2012 | Cle | Carter | Promoted to active roster | | | Before |
| 8/6/2012 | Cle | Carter | Promoted to active roster | | | Before |
| 8/6/2012 | Cle | Hyatt | Promoted to active roster | | | Before |
| 8/6/2012 | Cle | Nava | Demoted to reserve roster | | | Before |
| 8/6/2012 | Cle | Nava | Promoted to active roster | | | Before |
| 8/6/2012 | Cle | Thatcher | Demoted to reserve roster | | | Before |
| 8/6/2012 | Det | Bogusevic | Promoted to active roster | | | Before |
| 8/6/2012 | Det | Grandal | Demoted to reserve roster | | | Before |
| 8/6/2012 | Det | Schafer | Demoted to reserve roster | | | Before |
| 8/6/2012 | Det | Valle | Promoted to active roster | | | Before |
| 8/6/2012 | KC | Chamberlain | Promoted to active roster | | | Before |
| 8/6/2012 | KC | Havens | Promoted to active roster | | | Before |
| 8/6/2012 | LAA | Beltre | Promoted to active roster | | | Before |
| 8/6/2012 | LAA | Bonifacio | Demoted to reserve roster | | | Before |
| 8/6/2012 | LAA | Oramas | Promoted to active roster | | | Before |
| 8/6/2012 | LAA | Perez | Promoted to active roster | | | Before |
| 8/6/2012 | LAA | Rodriguez | Demoted to reserve roster | | | Before |
| 8/6/2012 | Min | Blackburn | Released | | | Before |
| 8/6/2012 | Min | Overbay | Signed | | | Before |
| 8/6/2012 | NYA | Dirks | Promoted to active roster | | | Before |
| 8/6/2012 | NYA | Downs | Demoted to reserve roster | | | Before |
| 8/6/2012 | Sea | Moreland | Promoted to active roster | | | Before |
| 8/6/2012 | Sea | Scott | Demoted to reserve roster | | | Before |
| 8/6/2012 | Tor | Herrera | Released | | | Before |
| 8/6/2012 | Tor | Lutz | Promoted to active roster | | | Before |
| 8/6/2012 | Tor | Pierzynski | Promoted to active roster | | | Before |
| 8/6/2012 | Tor | Ruiz | Demoted to reserve roster | | | Before |
| 8/9/2012 | Tex | Darvish | Acquired via trade | Pit | | After |
| 8/9/2012 | Tex | Drew | Acquired via trade | Pit | | After |
| 8/9/2012 | Tex | Reyes | Traded away | Pit | | After |
| 8/9/2012 | Tex | Wood | Traded away | Pit | | After |
| 8/10/2012 | Bos | Evans | Released | | | Before |
| 8/10/2012 | Det | Mayberry | Signed | | | Before |
| 8/10/2012 | Det | Schafer | Released | | | Before |
| 8/10/2012 | Tex | de losSantos | Released | | | Before |
| 8/10/2012 | Tex | Ogando | Promoted to active roster | | | Before |
| 8/12/2012 | Det | Carpenter | Traded away | Mil | | After |
| 8/12/2012 | Det | Detwiler | Traded away | Mil | | After |
| 8/12/2012 | Det | Estrada | Acquired via trade | Mil | | After |
| 8/12/2012 | Det | Lopez | Acquired via trade | Mil | | After |
| 8/12/2012 | Det | Morales | Acquired via trade | Mil | | After |
| 8/12/2012 | KC | Beavan | Acquired via trade | Pit | | After |
| 8/12/2012 | KC | Murphy | Acquired via trade | Pit | | After |
| 8/12/2012 | KC | Rzepczynski | Traded away | Pit | | After |
| 8/12/2012 | Min | Young | Acquired via trade | Atl | | After |
| 8/13/2012 | Cle | Delabar | Released | | | Before |
| 8/13/2012 | Cle | Hafner | Demoted to reserve roster | | | Before |
| 8/13/2012 | Cle | Konerko | Demoted to reserve roster | | | Before |
| 8/13/2012 | Cle | Martinez | Promoted to active roster | | | Before |
| 8/13/2012 | Cle | Sogard | Promoted to active roster | | | Before |
| 8/13/2012 | Det | Aybar | Promoted to active roster | | | Before |
| 8/13/2012 | Det | Bogusevic | Demoted to reserve roster | | | Before |
| 8/13/2012 | Det | Bogusevic | Promoted to active roster | | | Before |
| 8/13/2012 | Det | DeJesus | Demoted to reserve roster | | | Before |
| 8/13/2012 | Det | Diamond | Demoted to reserve roster | | | Before |
| 8/13/2012 | Det | Ely | Promoted to active roster | | | Before |
| 8/13/2012 | Det | Hoover | Demoted to reserve roster | | | Before |
| 8/13/2012 | Det | Mayberry | Released | | | Before |
| 8/13/2012 | KC | Carreno | Demoted to reserve roster | | | Before |
| 8/13/2012 | KC | Havens | Demoted to reserve roster | | | Before |
| 8/13/2012 | KC | Pennington | Promoted to active roster | | | Before |
| 8/13/2012 | Min | Bowden | Promoted to active roster | | | Before |
| 8/13/2012 | Min | Collmenter | Demoted to reserve roster | | | Before |
| 8/13/2012 | Min | Montgomery | Promoted to active roster | | | Before |
| 8/13/2012 | Min | Slama | Promoted to active roster | | | Before |
| 8/13/2012 | Min | Wells | Demoted to reserve roster | | | Before |
| 8/13/2012 | NYA | Damon | Demoted to reserve roster | | | Before |
| 8/13/2012 | NYA | Helton | Demoted to reserve roster | | | Before |
| 8/13/2012 | NYA | Hembree | Promoted to active roster | | | Before |
| 8/13/2012 | NYA | Sabathia | Demoted to reserve roster | | | Before |
| 8/13/2012 | NYA | Sierra | Promoted to active roster | | | Before |
| 8/16/2012 | Det | Beltre | Acquired via trade | Ari | | After |
| 8/16/2012 | Det | Chacin | Traded away | Ari | | After |
| 8/16/2012 | Det | Jones | Acquired via trade | Ari | | After |
| 8/16/2012 | Det | Stewart | Acquired via trade | Ari | | After |
| 8/16/2012 | Det | Valle | Traded away | Ari | | After |
| 8/17/2012 | ChA | Giavotella | Promoted to active roster | | | Before |
| 8/17/2012 | ChA | Lannan | Demoted to reserve roster | | | Before |
| 8/17/2012 | ChA | Lillibridge | Demoted to reserve roster | | | Before |
| 8/17/2012 | ChA | Mazzaro | Promoted to active roster | | | Before |
| 8/17/2012 | ChA | Moskos | Promoted to active roster | | | Before |
| 8/17/2012 | ChA | Nieuwenhuis | Demoted to reserve roster | | | Before |
| 8/17/2012 | ChA | Storen | Promoted to active roster | | | Before |
| 8/17/2012 | ChA | Wheeler | Released | | | Before |
| 8/17/2012 | Cle | Vazquez | Released | | | Before |
| 8/17/2012 | Det | Bogusevic | Demoted to reserve roster | | | Before |
| 8/17/2012 | Det | Gillespie | Demoted to reserve roster | | | Before |
| 8/17/2012 | Det | Joseph | Promoted to active roster | | | Before |
| 8/17/2012 | KC | Mastroianni | Signed | | | Before |
| 8/17/2012 | LAA | Fontenot | Released | | | Before |
| 8/17/2012 | LAA | Kennedy | Signed | | | Before |
| 8/17/2012 | LAA | Kennedy | Promoted to active roster | | | Before |
| 8/19/2012 | ChA | Loney | Traded away | Ari | | After |
| 8/19/2012 | ChA | Ruggiano | Acquired via trade | Ari | | After |
| 8/19/2012 | KC | Dillard | Acquired via trade | Ari | | After |
| 8/20/2012 | Bos | Gwynn | Signed | | | Before |
| 8/20/2012 | ChA | Lillibridge | Released | | | Before |
| 8/20/2012 | Cle | Cabrera | Signed | | | Before |
| 8/20/2012 | Cle | Carp | Demoted to reserve roster | | | Before |
| 8/20/2012 | Cle | Francisco | Promoted to active roster | | | Before |
| 8/20/2012 | Cle | Gomez | Promoted to active roster | | | Before |
| 8/20/2012 | Cle | Hunter | Promoted to active roster | | | Before |
| 8/20/2012 | Cle | Hyatt | Released | | | Before |
| 8/20/2012 | Cle | Konerko | Promoted to active roster | | | Before |
| 8/20/2012 | Cle | Sogard | Demoted to reserve roster | | | Before |
| 8/20/2012 | Cle | Tomlin | Demoted to reserve roster | | | Before |
| 8/20/2012 | KC | Plouffe | Promoted to active roster | | | Before |
| 8/20/2012 | KC | Seaton | Demoted to reserve roster | | | Before |
| 8/20/2012 | KC | Valdespin | Demoted to reserve roster | | | Before |
| 8/20/2012 | Min | Cashner | Demoted to reserve roster | | | Before |
| 8/20/2012 | Min | Hairston | Demoted to reserve roster | | | Before |
| 8/20/2012 | Min | Moylan | Promoted to active roster | | | Before |
| 8/20/2012 | Min | Overbay | Promoted to active roster | | | Before |
| 8/20/2012 | NYA | Downs | Promoted to active roster | | | Before |
| 8/20/2012 | Oak | Street | Demoted to reserve roster | | | Before |
| 8/20/2012 | Tor | Abreu | Demoted to reserve roster | | | Before |
| 8/20/2012 | Tor | Lemmerman | Released | | | Before |
| 8/20/2012 | Tor | Meyers | Released | | | Before |
| 8/20/2012 | Tor | Peacock | Promoted to active roster | | | Before |
| 8/20/2012 | Tor | Saito | Demoted to reserve roster | | | Before |
| 8/23/2012 | Bal | DeJesus | Acquired via trade | Det | | After |
| 8/23/2012 | Bal | Sipp | Traded away | Det | | After |
| 8/23/2012 | Det | DeJesus | Traded away | Bal | | After |
| 8/23/2012 | Det | Sipp | Acquired via trade | Bal | | After |
| 8/23/2012 | KC | Cruz | Acquired via trade | Col | | After |
| 8/23/2012 | KC | Gonzalez | Traded away | Col | | After |
| 8/23/2012 | KC | Haren | Acquired via trade | Col | | After |
| 8/23/2012 | KC | Mastroianni | Traded away | Col | | After |
| 8/24/2012 | Bos | Davis | Demoted to reserve roster | | | Before |
| 8/24/2012 | Bos | Fuentes | Demoted to reserve roster | | | Before |
| 8/24/2012 | Bos | Joseph | Signed | | | Before |
| 8/24/2012 | Bos | Marson | Promoted to active roster | | | Before |
| 8/24/2012 | Bos | Reynolds | Promoted to active roster | | | Before |
| 8/24/2012 | ChA | Lannan | Released | | | Before |
| 8/24/2012 | ChA | McHugh | Signed | | | Before |
| 8/24/2012 | Cle | Ross | Signed | | | Before |
| 8/24/2012 | Cle | Tomlin | Released | | | Before |
| 8/24/2012 | Det | Ely | Demoted to reserve roster | | | Before |
| 8/24/2012 | Det | Gillespie | Released | | | Before |
| 8/24/2012 | KC | Seaton | Released | | | Before |
| 8/24/2012 | Oak | Arias | Signed | | | Before |
| 8/24/2012 | Oak | Paterson | Released | | | Before |
| 8/24/2012 | Sea | Garcia | Promoted to active roster | | | Before |
| 8/24/2012 | Sea | Sandoval | Promoted to active roster | | | Before |
| 8/26/2012 | Det | Hoover | Traded away | Cin | | After |
| 8/26/2012 | Det | Suzuki | Acquired via trade | Cin | | After |
| 8/26/2012 | Det | Valverde | Acquired via trade | Oak | | After |
| 8/26/2012 | KC | Overbay | Acquired via trade | Min | | After |
| 8/26/2012 | Min | Overbay | Traded away | KC | | After |
| 8/26/2012 | Oak | Valverde | Traded away | Det | | After |
| 8/26/2012 | Tor | LaHair | Acquired via trade | Col | | After |
| 8/27/2012 | Bos | Bruce | Demoted to reserve roster | | | Before |
| 8/27/2012 | Bos | Ortiz | Promoted to active roster | | | Before |
| 8/27/2012 | Det | Alburquerque | Promoted to active roster | | | Before |
| 8/27/2012 | Det | Brothers | Demoted to reserve roster | | | Before |
| 8/27/2012 | Det | Joseph | Demoted to reserve roster | | | Before |
| 8/27/2012 | Det | Wright | Demoted to reserve roster | | | Before |
| 8/27/2012 | LAA | Bourjos | Demoted to reserve roster | | | Before |
| 8/27/2012 | LAA | James | Promoted to active roster | | | Before |
| 8/27/2012 | LAA | Oramas | Demoted to reserve roster | | | Before |
| 8/27/2012 | LAA | Pimentel | Promoted to active roster | | | Before |
| 8/27/2012 | NYA | Feliciano | Signed | | | Before |
| 8/27/2012 | NYA | Sabathia | Promoted to active roster | | | Before |
| 8/27/2012 | NYA | Sierra | Demoted to reserve roster | | | Before |
| 8/27/2012 | Oak | de Aza | Demoted to reserve roster | | | Before |
| 8/27/2012 | Oak | McCarthy | Promoted to active roster | | | Before |
| 8/27/2012 | Oak | Stanton | Promoted to active roster | | | Before |
| 8/28/2012 | KC | Beavan | Demoted to reserve roster | | | Before |
| 8/28/2012 | KC | Cowgill | Demoted to reserve roster | | | Before |
| 8/30/2012 | Cle | Aceves | Acquired via trade | NYA | | After |
| 8/30/2012 | Cle | Carter | Traded away | NYA | | After |
| 8/30/2012 | NYA | Aceves | Traded away | Cle | | After |
| 8/30/2012 | NYA | Carter | Acquired via trade | Cle | | After |
| 8/30/2012 | Tor | Smith | Acquired via trade | StL | | After |
| 8/31/2012 | Bos | Fuentes | Released | | | Before |
| 8/31/2012 | Min | Gomes | Signed | | | Before |
| 8/31/2012 | Min | Wells | Released | | | Before |
| 8/31/2012 | Sea | West | Released | | | Before |
| 8/31/2012 | Tor | Chen | Released | | | Before |
| 8/31/2012 | Tor | Lutz | Demoted to reserve roster | | | Before |
| 8/31/2012 | Tor | Maxwell | Signed | | | Before |
| 8/31/2012 | Tor | Maxwell | Promoted to active roster | | | Before |
| 8/31/2012 | Tor | Navarro | Demoted to reserve roster | | | Before |
| 8/31/2012 | Tor | Smith | Promoted to active roster | | | Before |
| 9/2/2012 | Det | Gallardo | Acquired via trade | SF | | After |
| 9/2/2012 | Det | Joseph | Traded away | SF | | After |
| 9/2/2012 | Det | Stewart | Traded away | Was | | After |
| 9/2/2012 | KC | Billingsley | Acquired via trade | Cin | | After |
| 9/2/2012 | KC | Borchering | Acquired via trade | Cin | | After |
| 9/2/2012 | KC | Pena | Traded away | NYA | | After |
| 9/2/2012 | KC | Sierra | Traded away | Cin | | After |
| 9/2/2012 | KC | Sierra | Acquired via trade | NYA | | After |
| 9/2/2012 | NYA | Pena | Acquired via trade | KC | | After |
| 9/2/2012 | NYA | Sierra | Traded away | KC | | After |
| 9/2/2012 | Oak | Zito | Traded away | SF | | After |
| 9/2/2012 | Sea | Freese | Traded away | Col | | After |
| 9/2/2012 | Sea | Gonzalez | Acquired via trade | Col | | After |
| 9/2/2012 | Sea | Jones | Traded away | Col | | After |
| 9/3/2012 | Bos | Bruce | Promoted to active roster | | | Before |
| 9/3/2012 | Bos | Cust | Promoted to active roster | | | Before |
| 9/3/2012 | Bos | Gwynn | Promoted to active roster | | | Before |
| 9/3/2012 | Bos | Joseph | Promoted to active roster | | | Before |
| 9/3/2012 | Bos | Ortiz | Demoted to reserve roster | | | Before |
| 9/3/2012 | ChA | Albaladejo | Demoted to reserve roster | | | Before |
| 9/3/2012 | ChA | Gregerson | Demoted to reserve roster | | | Before |
| 9/3/2012 | ChA | Kirkman | Demoted to reserve roster | | | Before |
| 9/3/2012 | ChA | Mayberry | Signed | | | Before |
| 9/3/2012 | ChA | Mayberry | Promoted to active roster | | | Before |
| 9/3/2012 | ChA | McPherson | Promoted to active roster | | | Before |
| 9/3/2012 | ChA | Moskos | Demoted to reserve roster | | | Before |
| 9/3/2012 | ChA | Niemann | Promoted to active roster | | | Before |
| 9/3/2012 | ChA | Peralta | Promoted to active roster | | | Before |
| 9/3/2012 | ChA | Reed | Demoted to reserve roster | | | Before |
| 9/3/2012 | ChA | Rogers | Promoted to active roster | | | Before |
| 9/3/2012 | Cle | Berkman | Promoted to active roster | | | Before |
| 9/3/2012 | Cle | Cabrera | Promoted to active roster | | | Before |
| 9/3/2012 | Cle | Francisco | Demoted to reserve roster | | | Before |
| 9/3/2012 | Cle | Francisco | Promoted to active roster | | | Before |
| 9/3/2012 | Cle | Martinez | Demoted to reserve roster | | | Before |
| 9/3/2012 | Cle | Martinez | Promoted to active roster | | | Before |
| 9/3/2012 | Cle | Thatcher | Promoted to active roster | | | Before |
| 9/3/2012 | Det | Brothers | Promoted to active roster | | | Before |
| 9/3/2012 | Det | Gallardo | Demoted to reserve roster | | | Before |
| 9/3/2012 | Det | Saunders | Demoted to reserve roster | | | Before |
| 9/3/2012 | Det | Saunders | Promoted to active roster | | | Before |
| 9/3/2012 | Det | Sipp | Demoted to reserve roster | | | Before |
| 9/3/2012 | KC | Bartlett | Released | | | Before |
| 9/3/2012 | KC | Towles | Signed | | | Before |
| 9/3/2012 | KC | Towles | Promoted to active roster | | | Before |
| 9/3/2012 | LAA | Hensley | Demoted to reserve roster | | | Before |
| 9/3/2012 | Oak | Arias | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | Crawford | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | Crosby | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | de Aza | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | Giambi | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | Marcum | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | Sanchez | Promoted to active roster | | | Before |
| 9/3/2012 | Oak | Santiago | Promoted to active roster | | | Before |
| 9/3/2012 | Sea | Worley | Demoted to reserve roster | | | Before |
| 9/3/2012 | Tor | Abreu | Promoted to active roster | | | Before |
| 9/3/2012 | Tor | Saito | Promoted to active roster | | | Before |
| 9/3/2012 | Tor | Uehara | Promoted to active roster | | | Before |
| 9/7/2012 | Cle | Carp | Promoted to active roster | | | Before |
| 9/7/2012 | Cle | Carraway | Promoted to active roster | | | Before |
| 9/7/2012 | Cle | Ross | Promoted to active roster | | | Before |
| 9/7/2012 | Det | Gallardo | Promoted to active roster | | | Before |
| 9/7/2012 | Det | Saunders | Demoted to reserve roster | | | Before |
| 9/7/2012 | Det | Stults | Signed | | | Before |
| 9/7/2012 | LAA | Ayala | Signed | | | Before |
| 9/7/2012 | LAA | Hensley | Released | | | Before |
| 9/8/2012 | Det | Arroyo | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Bogusevic | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Desmond | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Diamond | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Ely | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Grandal | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Saunders | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Sipp | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Stults | Promoted to active roster | | | Before |
| 9/8/2012 | Det | Wright | Promoted to active roster | | | Before |
| 9/8/2012 | LAA | Ayala | Promoted to active roster | | | Before |
| 9/10/2012 | Cle | Happ | Demoted to reserve roster | | | Before |
| 9/10/2012 | Det | Arroyo | Demoted to reserve roster | | | Before |
| 9/10/2012 | Det | Diamond | Demoted to reserve roster | | | Before |
| 9/10/2012 | Det | Ely | Demoted to reserve roster | | | Before |
| 9/10/2012 | Det | Stults | Demoted to reserve roster | | | Before |
| 9/10/2012 | KC | Arencibia | Promoted to active roster | | | Before |
| 9/10/2012 | KC | Towles | Demoted to reserve roster | | | Before |
| 9/10/2012 | NYA | Rodriguez | Promoted to active roster | | | Before |
| 9/10/2012 | NYA | Romine | Promoted to active roster | | | Before |
| 9/10/2012 | Sea | Ottavino | Signed | | | Before |
| 9/10/2012 | Sea | Scott | Released | | | Before |
| 9/10/2012 | Tex | Fryer | Signed | | | Before |
| 9/10/2012 | Tex | Fryer | Promoted to active roster | | | Before |
| 9/10/2012 | Tor | Cloyd | Promoted to active roster | | | Before |
| 9/10/2012 | Tor | Lutz | Promoted to active roster | | | Before |
| 9/10/2012 | Tor | Navarro | Promoted to active roster | | | Before |
| 9/10/2012 | Tor | Ruiz | Promoted to active roster | | | Before |
| 9/14/2012 | Bos | Cust | Demoted to reserve roster | | | Before |
| 9/14/2012 | Bos | Reynolds | Demoted to reserve roster | | | Before |
| 9/14/2012 | Bos | Tateyama | Promoted to active roster | | | Before |
| 9/14/2012 | Min | Okajima | Signed | | | Before |
| 9/14/2012 | Min | Wuertz | Released | | | Before |
| 9/17/2012 | Cle | Berkman | Demoted to reserve roster | | | Before |
| 9/17/2012 | LAA | Bourjos | Promoted to active roster | | | Before |
| 9/17/2012 | LAA | Chisenhall | Promoted to active roster | | | Before |
| 9/17/2012 | LAA | Kennedy | Demoted to reserve roster | | | Before |
| 9/17/2012 | LAA | Villar | Promoted to active roster | | | Before |
| 9/20/2012 | Oak | McCarthy | Demoted to reserve roster | | | Before |
| 9/21/2012 | Bos | Cust | Released | | | Before |
| 9/24/2012 | ChA | Solano | Signed | | | Before |
| 9/24/2012 | ChA | Torrealba | Released | | | Before |
| 9/24/2012 | Det | Arroyo | Promoted to active roster | | | Before |
| 9/24/2012 | Det | Beltre | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Diamond | Promoted to active roster | | | Before |
| 9/24/2012 | Det | Ely | Promoted to active roster | | | Before |
| 9/24/2012 | Det | Estrada | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Gallardo | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Goldschmidt | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Gordon | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Hamels | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Hellickson | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Lopez | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Montz | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Stults | Promoted to active roster | | | Before |
| 9/24/2012 | Det | Suzuki | Demoted to reserve roster | | | Before |
| 9/24/2012 | Det | Zimmermann | Demoted to reserve roster | | | Before |
| 9/28/2012 | ChA | Outman | Released | | | Before |
| 9/28/2012 | Cle | Putnam | Signed | | | Before |
| 9/28/2012 | Cle | Ross | Released | | | Before |
| 9/28/2012 | KC | Towles | Released | | | Before |
| 9/28/2012 | Min | Barton | Released | | | Before |
| 9/28/2012 | Min | Valbuena | Released | | | Before |
| 9/28/2012 | Oak | Street | Promoted to active roster | | | Before |
| 10/1/2012 | Bos | Davis | Promoted to active roster | | | Before |
| 10/1/2012 | Bos | Gwynn | Released | | | Before |
| 10/1/2012 | Bos | Reynolds | Promoted to active roster | | | Before |
| 10/1/2012 | ChA | Moskos | Released | | | Before |
| 10/1/2012 | NYA | Adams | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Atkins | Signed | | | Before |
| 10/1/2012 | NYA | Atkins | Promoted to active roster | | | Before |
| 10/1/2012 | NYA | Damon | Released | | | Before |
| 10/1/2012 | NYA | Feliciano | Released | | | Before |
| 10/1/2012 | NYA | Halladay | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Hernandez | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Hyatt | Signed | | | Before |
| 10/1/2012 | NYA | Hyatt | Promoted to active roster | | | Before |
| 10/1/2012 | NYA | Jeter | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Mauer | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Rodriguez | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Sabathia | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Soriano | Demoted to reserve roster | | | Before |
| 10/1/2012 | NYA | Wilson | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Beckett | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Clippard | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Colome | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Cuthbert | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Darvish | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Fielder | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Fielder | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Font | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Hampson | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Hawkins | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Ogando | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Oswalt | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Ramirez | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Rogers | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Romo | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Schoop | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Segura | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Shields | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Villarreal | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | White | Promoted to active roster | | | Before |
| 10/1/2012 | Tex | Wieters | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tex | Willingham | Demoted to reserve roster | | | Before |
| 10/1/2012 | Tor | Martinez | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Atkins | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Atkins | Promoted to active roster | | | Before |
| 10/3/2012 | NYA | Betancourt | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Downs | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Garcia | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Garcia | Promoted to active roster | | | Before |
| 10/3/2012 | NYA | Hembree | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Holland | Demoted to reserve roster | | | Before |
| 10/3/2012 | NYA | Runzler | Demoted to reserve roster | | | Before |
| 10/5/2012 | Bos | Bard | Demoted to reserve roster | | | Before |
| 10/5/2012 | Bos | Brach | Demoted to reserve roster | | | Before |
| 10/5/2012 | Bos | Brach | Promoted to active roster | | | Before |
| 10/5/2012 | Bos | Davis | Demoted to reserve roster | | | Before |
| 10/5/2012 | Bos | Heathcott | Promoted to active roster | | | Before |
| 10/5/2012 | Bos | Hudson | Demoted to reserve roster | | | Before |
| 10/5/2012 | Bos | Iwakuma | Demoted to reserve roster | | | Before |
| 10/5/2012 | Oak | Blanco | Demoted to reserve roster | | | Before |
| 10/5/2012 | Oak | Crosby | Demoted to reserve roster | | | Before |
| 10/5/2012 | Oak | Pina | Demoted to reserve roster | | | Before |
| 10/5/2012 | Oak | Santiago | Demoted to reserve roster | | | Before |
