| Transactions |
| Date | Team | Player | Type | OthTm | EffDate | When |
| 4/4/2012 | CTW | Davis,I | Promoted to active roster | | | Before |
| 4/4/2012 | CTW | Moss | Placed on Injured List | | 4/4/2012 | Before |
| 4/6/2012 | CTW | Bourjos | Promoted to active roster | | | Before |
| 4/6/2012 | CTW | Desmond | Placed on Injured List | | 4/6/2012 | Before |
| 4/7/2012 | BBG | Niese | Demoted to reserve roster | | | Before |
| 4/7/2012 | BBG | Dempster | Acquired via trade | RMO | | After |
| 4/7/2012 | BBG | Peacock (AG) | Traded away | RMO | | After |
| 4/7/2012 | BBG | Rivera,M | Traded away | RMO | | After |
| 4/7/2012 | NEP | Kearns | Promoted to active roster | | | Before |
| 4/7/2012 | NEP | Quentin | Placed on Injured List | | 4/7/2012 | Before |
| 4/8/2012 | CTW | Saunders,M | Placed on Injured List | | 4/9/2012 | Before |
| 4/10/2012 | ALP | Denorfia | Placed on Injured List | | 4/8/2012 | Before |
| 4/10/2012 | ALP | Johnson,Re | Promoted to active roster | | | Before |
| 4/10/2012 | CTW | Sappelt | Promoted to active roster | | | Before |
| 4/11/2012 | BBG | Betancourt,R | Promoted to active roster | | | Before |
| 4/11/2012 | BBG | Ruggiano | Placed on Injured List | | 4/9/2012 | Before |
| 4/11/2012 | GAR | Brach | Promoted to active roster | | | Before |
| 4/11/2012 | GAR | Duke | Demoted to reserve roster | | | Before |
| 4/13/2012 | ALP | Wilson,Ju | Demoted to reserve roster | | | Before |
| 4/13/2012 | ALP | Wright,W | Promoted to active roster | | | Before |
| 4/13/2012 | GAR | Beckham | Promoted to active roster | | | Before |
| 4/13/2012 | GAR | Gonzalez,Ma | Placed on Injured List | | 4/12/2012 | Before |
| 4/15/2012 | ALP | Colon,B | Placed on Injured List | | 4/15/2012 | Before |
| 4/15/2012 | ALP | Norris,B | Promoted to active roster | | | Before |
| 4/15/2012 | CIN | Kottaras,G | Promoted to active roster | | | Before |
| 4/15/2012 | CIN | Perez,S | Placed on Injured List | | 4/15/2012 | Before |
| 4/16/2012 | BBG | Betancourt,R | Demoted to reserve roster | | | Before |
| 4/16/2012 | BBG | Johnson,S | Promoted to active roster | | | Before |
| 4/17/2012 | BBG | Betancourt,R | Promoted to active roster | | | Before |
| 4/17/2012 | BBG | Johnson,S | Demoted to reserve roster | | | Before |
| 4/17/2012 | TEW | Lombardozzi | Promoted to active roster | | | Before |
| 4/17/2012 | TEW | Nelson | Placed on Injured List | | 4/16/2012 | Before |
| 4/19/2012 | NEP | Rauch | Promoted to active roster | | | Before |
| 4/19/2012 | NEP | Rodriguez,P | Demoted to reserve roster | | | Before |
| 4/20/2012 | ALP | Lowrie | Placed on Injured List | | 4/20/2012 | Before |
| 4/20/2012 | ALP | McDonald,Jo | Promoted to active roster | | | Before |
| 4/20/2012 | CTW | Bourjos | Demoted to reserve roster | | | Before |
| 4/20/2012 | CTW | Moss | Activated from Injured List | | | Before |
| 4/20/2012 | DLM | Crawford,C | Placed on Injured List | | 4/20/2012 | Before |
| 4/20/2012 | DLM | Guyer | Promoted to active roster | | | Before |
| 4/21/2012 | BAR | Bauer | Promoted to active roster | | | Before |
| 4/21/2012 | BAR | Corbin | Placed on Injured List | | 4/20/2012 | Before |
| 4/21/2012 | CTW | Desmond | Activated from Injured List | | | Before |
| 4/21/2012 | CTW | Sappelt | Demoted to reserve roster | | | Before |
| 4/22/2012 | CTW | Diamond | Demoted to reserve roster | | | Before |
| 4/22/2012 | CTW | Phelps,D | Promoted to active roster | | | Before |
| 4/24/2012 | TEW | Ford | Promoted to active roster | | | Before |
| 4/24/2012 | TEW | Wells,C | Placed on Injured List | | 4/23/2012 | Before |
| 4/26/2012 | ALP | Shaw | Promoted to active roster | | | Before |
| 4/26/2012 | ALP | Thornburg | Demoted to reserve roster | | | Before |
| 4/26/2012 | BBG | Betancourt,R | Demoted to reserve roster | | | Before |
| 4/26/2012 | BBG | Ruggiano | Activated from Injured List | | | Before |
| 4/26/2012 | BBG | Valdes,R | Promoted to active roster | | | Before |
| 4/26/2012 | BBG | Veal | Demoted to reserve roster | | | Before |
| 4/26/2012 | CTW | Forsythe | Demoted to reserve roster | | | Before |
| 4/26/2012 | CTW | Saunders,M | Activated from Injured List | | | Before |
| 4/28/2012 | CIN | LeCure | Promoted to active roster | | | Before |
| 4/28/2012 | CIN | Perez,O | Placed on Injured List | | 4/28/2012 | Before |
| 4/28/2012 | GAR | Beckham | Demoted to reserve roster | | | Before |
| 4/28/2012 | GAR | Gonzalez,Ma | Activated from Injured List | | | Before |
| 5/1/2012 | ALP | Colon,B | Activated from Injured List | | | Before |
| 5/1/2012 | ALP | Maholm | Demoted to reserve roster | | | Before |
| 5/3/2012 | ALP | Castillo,W | Placed on Injured List | | 5/3/2012 | Before |
| 5/3/2012 | ALP | Gimenez,C | Promoted to active roster | | | Before |
| 5/5/2012 | TEW | Nelson | Activated from Injured List | | | Before |
| 5/5/2012 | TEW | Rodriguez,Al | Placed on Injured List | | 5/5/2012 | Before |
| 5/6/2012 | ALP | Lowrie | Activated from Injured List | | | Before |
| 5/6/2012 | ALP | McDonald,Jo | Demoted to reserve roster | | | Before |
| 5/6/2012 | BAR | Brown,D | Promoted to active roster | | | Before |
| 5/6/2012 | BAR | Martinez,JD | Placed on Injured List | | 5/6/2012 | Before |
| 5/6/2012 | DLM | Crawford,C | Activated from Injured List | | | Before |
| 5/6/2012 | DLM | Guyer | Demoted to reserve roster | | | Before |
| 5/7/2012 | CEN | Capuano | Demoted to reserve roster | | | Before |
| 5/7/2012 | CEN | Floyd | Promoted to active roster | | | Before |
| 5/7/2012 | NEP | Bailey,H | Promoted to active roster | | | Before |
| 5/7/2012 | NEP | Morrow | Promoted to active roster | | | Before |
| 5/7/2012 | NEP | Parker,J | Demoted to reserve roster | | | Before |
| 5/7/2012 | NEP | Quintana | Demoted to reserve roster | | | Before |
| 5/9/2012 | CIN | Allen,C | Demoted to reserve roster | | | Before |
| 5/9/2012 | CIN | Storen | Promoted to active roster | | | Before |
| 5/10/2012 | ALP | Denorfia | Activated from Injured List | | | Before |
| 5/10/2012 | ALP | Johnson,Re | Demoted to reserve roster | | | Before |
| 5/10/2012 | CIN | Kottaras,G | Demoted to reserve roster | | | Before |
| 5/10/2012 | CIN | Perez,S | Activated from Injured List | | | Before |
| 5/11/2012 | NEP | Kearns | Demoted to reserve roster | | | Before |
| 5/11/2012 | NEP | Quentin | Activated from Injured List | | | Before |
| 5/14/2012 | CIN | Iglesias | Demoted to reserve roster | | | Before |
| 5/14/2012 | CIN | Ramirez,Al | Promoted to active roster | | | Before |
| 5/14/2012 | GAR | Cecil | Promoted to active roster | | | Before |
| 5/14/2012 | GAR | Neshek | Demoted to reserve roster | | | Before |
| 5/16/2012 | CTW | Ross,C | Placed on Injured List | | 5/16/2012 | Before |
| 5/16/2012 | CTW | Tazawa | Promoted to active roster | | | Before |
| 5/19/2012 | DLM | Duffy | Demoted to reserve roster | | | Before |
| 5/20/2012 | ALP | Colon,B | Placed on Injured List | | 5/20/2012 | Before |
| 5/20/2012 | ALP | Harvey | Demoted to reserve roster | | | Before |
| 5/20/2012 | ALP | Maholm | Promoted to active roster | | | Before |
| 5/20/2012 | ALP | Villarreal,B | Promoted to active roster | | | Before |
| 5/20/2012 | DLM | Ramos,AJ | Promoted to active roster | | | Before |
| 5/21/2012 | DLM | Crawford,C | Demoted to reserve roster | | | Before |
| 5/22/2012 | ALP | Castillo,W | Activated from Injured List | | | Before |
| 5/22/2012 | ALP | Gimenez,C | Demoted to reserve roster | | | Before |
| 5/25/2012 | DLM | Barney | Promoted to active roster | | | Before |
| 5/26/2012 | TEW | Archer | Promoted to active roster | | | Before |
| 5/26/2012 | TEW | Thole | Placed on Injured List | | 5/26/2012 | Before |
| 5/26/2012 | TEW | Vogelsong | Placed on Injured List | | 5/26/2012 | Before |
| 5/26/2012 | TEW | Vogt | Promoted to active roster | | | Before |
| 5/27/2012 | GAR | Ankiel | Promoted to active roster | | | Before |
| 5/27/2012 | GAR | Chen,B | Promoted to active roster | | | Before |
| 5/27/2012 | GAR | Marte,S | Demoted to reserve roster | | | Before |
| 5/27/2012 | GAR | Ross,T | Demoted to reserve roster | | | Before |
| 5/27/2012 | TEW | Ford | Demoted to reserve roster | | | Before |
| 5/27/2012 | TEW | Wells,C | Activated from Injured List | | | Before |
| 5/29/2012 | BAR | Bauer | Demoted to reserve roster | | | Before |
| 5/29/2012 | GAR | Beckham | Promoted to active roster | | | Before |
| 5/29/2012 | GAR | Turner,Ju | Demoted to reserve roster | | | Before |
| 5/30/2012 | GAR | Arrieta | Placed on Injured List | | 5/30/2012 | Before |
| 5/30/2012 | GAR | Richards | Promoted to active roster | | | Before |
| 5/31/2012 | BAR | Corbin | Activated from Injured List | | | Before |
| 5/31/2012 | BAR | Minor | Placed on Injured List | | 5/29/2012 | Before |
| 6/1/2012 | GAR | Jones,An | Promoted to active roster | | | Before |
| 6/1/2012 | GAR | Van Slyke | Demoted to reserve roster | | | Before |
| 6/4/2012 | ALP | Colon,B | Activated from Injured List | | | Before |
| 6/4/2012 | ALP | Webb | Demoted to reserve roster | | | Before |
| 6/4/2012 | BBG | Dempster | Placed on Injured List | | 6/4/2012 | Before |
| 6/4/2012 | BBG | Griffin | Demoted to reserve roster | | | Before |
| 6/4/2012 | BBG | Johnson,S | Promoted to active roster | | | Before |
| 6/4/2012 | BBG | Niese | Promoted to active roster | | | Before |
| 6/4/2012 | DLM | Blanco,H | Promoted to active roster | | | Before |
| 6/4/2012 | DLM | Lucroy | Placed on Injured List | | 6/3/2012 | Before |
| 6/5/2012 | BAR | Abad | Promoted to active roster | | | Before |
| 6/5/2012 | BAR | Adams,Ma | Promoted to active roster | | | Before |
| 6/5/2012 | BAR | Martinez,JD | Activated from Injured List | | | Before |
| 6/5/2012 | BAR | Torres,C | Demoted to reserve roster | | | Before |
| 6/5/2012 | BAR | Tulowitzki | Demoted to reserve roster | | | Before |
| 6/6/2012 | ALP | Delabar,S | Promoted to active roster | | | Before |
| 6/6/2012 | ALP | Ogando | Demoted to reserve roster | | | Before |
| 6/7/2012 | GAR | Grandal | Demoted to reserve roster | | | Before |
| 6/7/2012 | GAR | Hughes,P | Placed on Injured List | | 6/7/2012 | Before |
| 6/7/2012 | GAR | McKenry | Promoted to active roster | | | Before |
| 6/7/2012 | GAR | Zito | Promoted to active roster | | | Before |
| 6/7/2012 | NEP | Lynn | Demoted to reserve roster | | | Before |
| 6/7/2012 | NEP | Quintana | Promoted to active roster | | | Before |
| 6/10/2012 | CIN | Ciriaco | Demoted to reserve roster | | | Before |
| 6/10/2012 | CIN | Frieri | Promoted to active roster | | | Before |
| 6/10/2012 | CIN | Hanigan | Demoted to reserve roster | | | Before |
| 6/10/2012 | CIN | Herrera,E | Promoted to active roster | | | Before |
| 6/10/2012 | CIN | Konerko | Demoted to reserve roster | | | Before |
| 6/10/2012 | CIN | Martin,L | Promoted to active roster | | | Before |
| 6/10/2012 | TEW | Archer | Demoted to reserve roster | | | Before |
| 6/10/2012 | TEW | Thole | Activated from Injured List | | | Before |
| 6/10/2012 | TEW | Vogelsong | Activated from Injured List | | | Before |
| 6/10/2012 | TEW | Vogt | Demoted to reserve roster | | | Before |
| 6/13/2012 | CTW | Phelps,D | Demoted to reserve roster | | | Before |
| 6/13/2012 | CTW | Ross,C | Activated from Injured List | | | Before |
| 6/15/2012 | BBG | Horst | Promoted to active roster | | | Before |
| 6/15/2012 | BBG | Valdes,R | Demoted to reserve roster | | | Before |
| 6/15/2012 | NEP | Quentin | Placed on Injured List | | 6/15/2012 | Before |
| 6/15/2012 | NEP | Viciedo | Promoted to active roster | | | Before |
| 6/16/2012 | ALP | Castillo,W | Demoted to reserve roster | | | Before |
| 6/16/2012 | ALP | Gimenez,C | Promoted to active roster | | | Before |
| 6/16/2012 | ALP | Lowrie | Demoted to reserve roster | | | Before |
| 6/16/2012 | ALP | McDonald,Jo | Promoted to active roster | | | Before |
| 6/18/2012 | ALP | Santos,S | Promoted to active roster | | | Before |
| 6/18/2012 | ALP | Villarreal,B | Demoted to reserve roster | | | Before |
| 6/18/2012 | GAR | Arrieta | Activated from Injured List | | | Before |
| 6/18/2012 | GAR | Gee | Demoted to reserve roster | | | Before |
| 6/18/2012 | NEP | Iannetta | Promoted to active roster | | | Before |
| 6/18/2012 | NEP | Kratz | Demoted to reserve roster | | | Before |
| 6/20/2012 | GAR | Aviles | Promoted to active roster | | | Before |
| 6/20/2012 | GAR | Carpenter,M | Demoted to reserve roster | | | Before |
| 6/21/2012 | BBG | Bautista | Placed on Injured List | | 6/19/2012 | Before |
| 6/21/2012 | BBG | Betancourt,R | Promoted to active roster | | | Before |
| 6/21/2012 | CIN | Simon | Promoted to active roster | | | Before |
| 6/21/2012 | CIN | Storen | Demoted to reserve roster | | | Before |
| 6/22/2012 | ALP | Ellsbury | Demoted to reserve roster | | | Before |
| 6/22/2012 | ALP | Torres,An | Promoted to active roster | | | Before |
| 6/22/2012 | DLM | Edgin | Demoted to reserve roster | | | Before |
| 6/23/2012 | DLM | Jepsen | Demoted to reserve roster | | | Before |
| 6/23/2012 | DLM | Lowe,M | Promoted to active roster | | | Before |
| 6/23/2012 | DLM | O'Flaherty | Promoted to active roster | | | Before |
| 6/23/2012 | DLM | Putnam | Promoted to active roster | | | Before |
| 6/23/2012 | DLM | Ramos,AJ | Demoted to reserve roster | | | Before |
| 6/24/2012 | ALP | McLouth | Promoted to active roster | | | Before |
| 6/24/2012 | ALP | Schierholtz | Demoted to reserve roster | | | Before |
| 6/25/2012 | GAR | Abreu,B | Promoted to active roster | | | After |
| 6/25/2012 | GAR | Dyson,J | Demoted to reserve roster | | | After |
| 6/26/2012 | GAR | Manship | Promoted to active roster | | | Before |
| 6/26/2012 | GAR | McGee | Demoted to reserve roster | | | Before |
| 6/26/2012 | TEW | Lombardozzi | Demoted to reserve roster | | | Before |
| 6/26/2012 | TEW | Vogt | Promoted to active roster | | | Before |
| 6/27/2012 | DLM | Pestano | Promoted to active roster | | | Before |
| 6/27/2012 | DLM | Putnam | Demoted to reserve roster | | | Before |
| 6/27/2012 | NEP | Avilan | Demoted to reserve roster | | | Before |
| 6/27/2012 | NEP | Choate | Promoted to active roster | | | Before |
| 6/28/2012 | ALP | Santos,S | Demoted to reserve roster | | | Before |
| 6/28/2012 | ALP | Webb | Promoted to active roster | | | Before |
| 6/28/2012 | GAR | DeJesus | Promoted to active roster | | | Before |
| 6/28/2012 | GAR | Gonzalez,Ma | Demoted to reserve roster | | | Before |
| 6/29/2012 | BAR | Minor | Activated from Injured List | | | Before |
| 6/29/2012 | BAR | Rizzo | Demoted to reserve roster | | | Before |
| 7/3/2012 | ALP | Jones,C | Demoted to reserve roster | | | Before |
| 7/3/2012 | ALP | Lowrie | Promoted to active roster | | | Before |
| 7/3/2012 | CIN | Frieri | Demoted to reserve roster | | | Before |
| 7/3/2012 | CIN | Perez,C | Promoted to active roster | | | Before |
| 7/3/2012 | CIN | Pettitte | Promoted to active roster | | | Before |
| 7/3/2012 | CIN | Vargas | Demoted to reserve roster | | | Before |
| 7/3/2012 | DLM | Francisco,J | Demoted to reserve roster | | | Before |
| 7/3/2012 | DLM | Guyer | Promoted to active roster | | | Before |
| 7/3/2012 | DLM | Lucroy | Activated from Injured List | | | Before |
| 7/3/2012 | DLM | Shoppach | Demoted to reserve roster | | | Before |
| 7/4/2012 | BBG | Dempster | Activated from Injured List | | | Before |
| 7/4/2012 | BBG | Johnson,S | Demoted to reserve roster | | | Before |
| 7/4/2012 | DLM | De Fratus | Promoted to active roster | | | Before |
| 7/4/2012 | DLM | Frasor | Demoted to reserve roster | | | Before |
| 7/4/2012 | DLM | Gillaspie | Promoted to active roster | | | Before |
| 7/4/2012 | DLM | Plouffe | Placed on Injured List | | 7/4/2012 | Before |
| 7/4/2012 | DLM | Qualls,C | Demoted to reserve roster | | | Before |
| 7/4/2012 | DLM | Rapada | Promoted to active roster | | | Before |
| 7/5/2012 | ALP | Beltran | Placed on Injured List | | 7/5/2012 | Before |
| 7/5/2012 | ALP | Jones,C | Promoted to active roster | | | Before |
| 7/5/2012 | NEP | Iannetta | Demoted to reserve roster | | | Before |
| 7/5/2012 | NEP | Lynn | Promoted to active roster | | | Before |
| 7/5/2012 | NEP | Nieves,W | Promoted to active roster | | | Before |
| 7/5/2012 | NEP | Peavy | Demoted to reserve roster | | | Before |
| 7/5/2012 | NEP | Peralta,Jo | Promoted to active roster | | | Before |
| 7/5/2012 | NEP | Quentin | Activated from Injured List | | | Before |
| 7/5/2012 | NEP | Thayer | Demoted to reserve roster | | | Before |
| 7/5/2012 | NEP | Viciedo | Demoted to reserve roster | | | Before |
| 7/7/2012 | NEP | Jaso | Placed on Injured List | | 7/6/2012 | Before |
| 7/7/2012 | NEP | Pacheco | Promoted to active roster | | | Before |
| 7/11/2012 | DLM | Furcal | Promoted to active roster | | | Before |
| 7/11/2012 | DLM | Gillaspie | Demoted to reserve roster | | | Before |
| 7/12/2012 | CTW | Iwakuma | Demoted to reserve roster | | | Before |
| 7/12/2012 | CTW | Phelps,D | Promoted to active roster | | | Before |
| 7/12/2012 | DLM | Guyer | Demoted to reserve roster | | | Before |
| 7/12/2012 | TEW | Archer | Promoted to active roster | | | Before |
| 7/12/2012 | TEW | Garza | Demoted to reserve roster | | | Before |
| 7/12/2012 | TEW | Hoover | Promoted to active roster | | | Before |
| 7/12/2012 | TEW | Patton | Placed on Injured List | | 7/12/2012 | Before |
| 7/13/2012 | ALP | Villarreal,B | Traded away | FDH | | After |
| 7/13/2012 | GAR | Arrieta | Demoted to reserve roster | | | Before |
| 7/13/2012 | GAR | Broxton | Demoted to reserve roster | | | Before |
| 7/13/2012 | GAR | Hughes,P | Activated from Injured List | | | Before |
| 7/13/2012 | GAR | Koehler | Promoted to active roster | | | Before |
| 7/13/2012 | GAR | Roenicke | Promoted to active roster | | | Before |
| 7/13/2012 | GAR | Sipp | Demoted to reserve roster | | | Before |
| 7/13/2012 | NEP | Peavy | Promoted to active roster | | | Before |
| 7/13/2012 | NEP | Quintana | Placed on Injured List | | 7/12/2012 | Before |
| 7/13/2012 | NEP | Viciedo | Promoted to active roster | | | Before |
| 7/13/2012 | NEP | Willingham | Placed on Injured List | | 7/12/2012 | Before |
| 7/14/2012 | CTW | Anderson,BF | Promoted to active roster | | | Before |
| 7/14/2012 | CTW | Kemp | Placed on Injured List | | 7/14/2012 | Before |
| 7/15/2012 | CEN | Medlen | Demoted to reserve roster | | | Before |
| 7/15/2012 | CTW | Fiers | Demoted to reserve roster | | | Before |
| 7/15/2012 | CTW | Loup | Promoted to active roster | | | Before |
| 7/17/2012 | CEN | Capuano | Promoted to active roster | | | Before |
| 7/17/2012 | CEN | Dotel | Demoted to reserve roster | | | Before |
| 7/19/2012 | BBG | Bautista | Activated from Injured List | | | Before |
| 7/19/2012 | BBG | Bundy | Promoted to active roster | | | Before |
| 7/19/2012 | BBG | Crain | Demoted to reserve roster | | | Before |
| 7/19/2012 | BBG | Dempster | Placed on Injured List | | 7/18/2012 | Before |
| 7/19/2012 | BBG | Hamilton | Placed on Injured List | | 7/18/2012 | Before |
| 7/19/2012 | BBG | Niemann | Promoted to active roster | | | Before |
| 7/19/2012 | CEN | Wright,J | Promoted to active roster | | | Before |
| 7/19/2012 | GAR | Bonifacio | Demoted to reserve roster | | | Before |
| 7/19/2012 | GAR | Calhoun | Promoted to active roster | | | Before |
| 7/19/2012 | GAR | Manship | Demoted to reserve roster | | | Before |
| 7/19/2012 | GAR | Sheets | Promoted to active roster | | | Before |
| 7/20/2012 | BAR | Cobb | Demoted to reserve roster | | | Before |
| 7/20/2012 | BAR | Coleman,L | Demoted to reserve roster | | | Before |
| 7/20/2012 | BAR | Furbush | Promoted to active roster | | | Before |
| 7/20/2012 | BAR | Lopez,Ja | Promoted to active roster | | | Before |
| 7/20/2012 | NEP | Murphy,Do | Placed on Injured List | | 7/16/2012 | Before |
| 7/20/2012 | NEP | Ransom,C | Promoted to active roster | | | Before |
| 7/21/2012 | ALP | Beltran | Activated from Injured List | | | Before |
| 7/21/2012 | ALP | Torres,An | Demoted to reserve roster | | | Before |
| 7/21/2012 | CEN | Sabathia | Acquired via trade | SOI | | After |
| 7/22/2012 | ALP | Reed | Acquired via trade | NYD | | After |
| 7/22/2012 | ALP | Torres,An | Traded away | NYD | | After |
| 7/22/2012 | ALP | Webb | Traded away | NYD | | After |
| 7/22/2012 | BBG | Bundy | Demoted to reserve roster | | | Before |
| 7/22/2012 | TEW | Middlebrooks | Demoted to reserve roster | | | Before |
| 7/22/2012 | TEW | Rodriguez,Al | Activated from Injured List | | | Before |
| 7/23/2012 | BBG | Lewis,C | Promoted to active roster | | | Before |
| 7/23/2012 | CEN | Hammel | Demoted to reserve roster | | | Before |
| 7/23/2012 | GAR | Holt | Demoted to reserve roster | | | Before |
| 7/23/2012 | GAR | Turner,Ju | Promoted to active roster | | | Before |
| 7/24/2012 | DLM | De Fratus | Demoted to reserve roster | | | Before |
| 7/24/2012 | DLM | Duensing | Demoted to reserve roster | | | Before |
| 7/24/2012 | DLM | Hanson | Promoted to active roster | | | Before |
| 7/24/2012 | DLM | Millwood | Promoted to active roster | | | Before |
| 7/24/2012 | DLM | Norberto | Promoted to active roster | | | Before |
| 7/25/2012 | ALP | Lind | Demoted to reserve roster | | | Before |
| 7/25/2012 | ALP | Tolleson,St | Promoted to active roster | | | Before |
| 7/26/2012 | BAR | Alvarez,H | Demoted to reserve roster | | | Before |
| 7/26/2012 | BAR | Corbin | Demoted to reserve roster | | | Before |
| 7/26/2012 | BAR | Happ,JA | Demoted to reserve roster | | | Before |
| 7/26/2012 | BAR | Hawkins | Promoted to active roster | | | Before |
| 7/26/2012 | BAR | Mikolas | Promoted to active roster | | | Before |
| 7/26/2012 | BAR | Scheppers | Promoted to active roster | | | Before |
| 7/26/2012 | BAR | Walden | Promoted to active roster | | | Before |
| 7/26/2012 | BAR | Watson | Demoted to reserve roster | | | Before |
| 7/26/2012 | CIN | Miller,A | Demoted to reserve roster | | | Before |
| 7/26/2012 | CIN | Perez,O | Activated from Injured List | | | Before |
| 7/26/2012 | CTW | Forsythe | Promoted to active roster | | | Before |
| 7/26/2012 | CTW | Moss | Demoted to reserve roster | | | Before |
| 7/26/2012 | CTW | Phelps,D | Demoted to reserve roster | | | Before |
| 7/26/2012 | CTW | Hester | Traded away | RMO | | After |
| 7/26/2012 | CTW | Hudson,T | Acquired via trade | RMO | | After |
| 7/26/2012 | CTW | Kontos | Traded away | RMO | | After |
| 7/26/2012 | GAR | Ankiel | Demoted to reserve roster | | | Before |
| 7/26/2012 | GAR | Garcia,F | Promoted to active roster | | | Before |
| 7/26/2012 | GAR | Huff,A | Promoted to active roster | | | Before |
| 7/26/2012 | GAR | Richards | Demoted to reserve roster | | | Before |
| 7/27/2012 | NEP | Morrow | Demoted to reserve roster | | | Before |
| 7/27/2012 | NEP | Quintana | Activated from Injured List | | | Before |
| 7/27/2012 | NEP | Viciedo | Demoted to reserve roster | | | Before |
| 7/27/2012 | NEP | Willingham | Activated from Injured List | | | Before |
| 7/29/2012 | CEN | Hughes,J | Promoted to active roster | | | Before |
| 7/29/2012 | CEN | Ramos,C | Demoted to reserve roster | | | Before |
| 7/29/2012 | CIN | Frieri | Promoted to active roster | | | Before |
| 7/29/2012 | CIN | Perkins | Demoted to reserve roster | | | Before |
| 7/29/2012 | DLM | Furcal | Demoted to reserve roster | | | Before |
| 7/29/2012 | DLM | Plouffe | Activated from Injured List | | | Before |
| 7/30/2012 | CIN | Martin,L | Demoted to reserve roster | | | Before |
| 7/30/2012 | CIN | Young,E | Promoted to active roster | | | Before |
| 7/30/2012 | GAR | Carpenter,M | Promoted to active roster | | | Before |
| 7/30/2012 | GAR | Turner,Ju | Demoted to reserve roster | | | Before |
| 7/31/2012 | CEN | Montero,J | Demoted to reserve roster | | | Before |
| 7/31/2012 | CEN | Pina | Promoted to active roster | | | Before |
| 7/31/2012 | CIN | Johnson,E | Traded away | BRK | | After |
| 7/31/2012 | CTW | Burnett,S | Traded away | NYD | | After |
| 7/31/2012 | CTW | Galarraga | Acquired via trade | NYD | | After |
| 7/31/2012 | CTW | Greene,Ty | Traded away | RMO | | After |
| 7/31/2012 | DLM | Britton | Demoted to reserve roster | | | Before |
| 7/31/2012 | DLM | Furcal | Promoted to active roster | | | Before |
| 7/31/2012 | DLM | Santana | Promoted to active roster | | | Before |
| 7/31/2012 | DLM | Scherzer | Demoted to reserve roster | | | Before |
| 7/31/2012 | TEW | Clevenger | Traded away | BRK | | After |
| 7/31/2012 | TEW | Cuddyer | Acquired via trade | BRK | | After |
| 7/31/2012 | TEW | Youkilis | Acquired via trade | BRK | | After |
| 8/1/2012 | CTW | Buchholz | Demoted to reserve roster | | | Before |
| 8/1/2012 | CTW | Peralta,W | Promoted to active roster | | | Before |
| 8/1/2012 | TEW | Archer | Demoted to reserve roster | | | Before |
| 8/1/2012 | TEW | Billingsley | Promoted to active roster | | | Before |
| 8/1/2012 | TEW | Markakis | Demoted to reserve roster | | | Before |
| 8/1/2012 | TEW | Vogt | Demoted to reserve roster | | | Before |
| 8/2/2012 | BBG | Dempster | Activated from Injured List | | | Before |
| 8/2/2012 | BBG | Hamilton | Activated from Injured List | | | Before |
| 8/2/2012 | BBG | Lewis,C | Demoted to reserve roster | | | Before |
| 8/2/2012 | BBG | Niemann | Demoted to reserve roster | | | Before |
| 8/2/2012 | CEN | Carlin | Promoted to active roster | | | Before |
| 8/2/2012 | CEN | Pina | Demoted to reserve roster | | | Before |
| 8/6/2012 | CTW | Anderson,BF | Demoted to reserve roster | | | Before |
| 8/6/2012 | CTW | Ramirez,Er | Promoted to active roster | | | Before |
| 8/7/2012 | CTW | Davis,I | Demoted to reserve roster | | | Before |
| 8/7/2012 | CTW | Kemp | Activated from Injured List | | | Before |
| 8/7/2012 | GAR | Brach | Demoted to reserve roster | | | Before |
| 8/7/2012 | GAR | Carpenter,M | Demoted to reserve roster | | | Before |
| 8/7/2012 | GAR | Gonzalez,Ma | Promoted to active roster | | | Before |
| 8/7/2012 | GAR | McGee | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | Colon,B | Demoted to reserve roster | | | Before |
| 8/8/2012 | ALP | Descalso | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | Donaldson | Demoted to reserve roster | | | Before |
| 8/8/2012 | ALP | Fister | Demoted to reserve roster | | | Before |
| 8/8/2012 | ALP | Gomez,J | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | Johnson,Re | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | Jones,C | Demoted to reserve roster | | | Before |
| 8/8/2012 | ALP | Machi | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | Mazzaro | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | McDonald,Jo | Demoted to reserve roster | | | Before |
| 8/8/2012 | ALP | Schierholtz | Promoted to active roster | | | Before |
| 8/8/2012 | ALP | Wright,W | Demoted to reserve roster | | | Before |
| 8/8/2012 | NEP | Belisario | Demoted to reserve roster | | | Before |
| 8/8/2012 | NEP | Breslow,C | Promoted to active roster | | | Before |
| 8/8/2012 | NEP | Jaso | Activated from Injured List | | | Before |
| 8/8/2012 | NEP | Nieves,W | Demoted to reserve roster | | | Before |
| 8/9/2012 | ALP | Carpenter,DD | Promoted to active roster | | | Before |
| 8/9/2012 | ALP | Maholm | Demoted to reserve roster | | | Before |
| 8/9/2012 | CTW | Davis,I | Promoted to active roster | | | Before |
| 8/9/2012 | CTW | Kemp | Placed on Injured List | | 8/9/2012 | Before |
| 8/9/2012 | NEP | Ludwick | Demoted to reserve roster | | | Before |
| 8/9/2012 | TEW | Lombardozzi | Promoted to active roster | | | Before |
| 8/9/2012 | TEW | Nelson | Demoted to reserve roster | | | Before |
| 8/9/2012 | TEW | Parnell | Demoted to reserve roster | | | Before |
| 8/9/2012 | TEW | Patton | Activated from Injured List | | | Before |
| 8/11/2012 | NEP | Colvin | Promoted to active roster | | | Before |
| 8/12/2012 | CEN | Hughes,J | Demoted to reserve roster | | | Before |
| 8/12/2012 | CEN | Kirkman | Promoted to active roster | | | Before |
| 8/12/2012 | CEN | Mijares,J | Promoted to active roster | | | Before |
| 8/12/2012 | CEN | Wright,J | Demoted to reserve roster | | | Before |
| 8/13/2012 | BAR | Abad | Demoted to reserve roster | | | Before |
| 8/13/2012 | BAR | Hill,R | Promoted to active roster | | | Before |
| 8/13/2012 | BAR | Martinez,JD | Demoted to reserve roster | | | Before |
| 8/13/2012 | BAR | Ruf | Promoted to active roster | | | Before |
| 8/13/2012 | CIN | Karstens | Promoted to active roster | | | Before |
| 8/13/2012 | CIN | Perez,O | Demoted to reserve roster | | | Before |
| 8/14/2012 | GAR | Burroughs | Promoted to active roster | | | Before |
| 8/14/2012 | GAR | Duda | Demoted to reserve roster | | | Before |
| 8/14/2012 | NEP | Murphy,Do | Activated from Injured List | | | Before |
| 8/14/2012 | NEP | Ransom,C | Demoted to reserve roster | | | Before |
| 8/15/2012 | ALP | Machi | Demoted to reserve roster | | | Before |
| 8/15/2012 | ALP | Ogando | Promoted to active roster | | | Before |
| 8/15/2012 | CTW | Motte | Promoted to active roster | | | Before |
| 8/15/2012 | CTW | O'Day | Demoted to reserve roster | | | Before |
| 8/16/2012 | CIN | Hanigan | Promoted to active roster | | | Before |
| 8/16/2012 | CIN | Perez,S | Placed on Injured List | | 8/16/2012 | Before |
| 8/16/2012 | GAR | Koehler | Demoted to reserve roster | | | Before |
| 8/16/2012 | GAR | Marte,S | Promoted to active roster | | | Before |
| 8/17/2012 | CIN | Gonzalez,G | Placed on Injured List | | 8/17/2012 | Before |
| 8/17/2012 | CIN | Vargas | Promoted to active roster | | | Before |
| 8/17/2012 | GAR | Garcia,F | Placed on Injured List | | 8/17/2012 | Before |
| 8/17/2012 | NEP | Colvin | Demoted to reserve roster | | | Before |
| 8/17/2012 | NEP | Ransom,C | Promoted to active roster | | | Before |
| 8/18/2012 | BAR | Cruz,N | Demoted to reserve roster | | | Before |
| 8/18/2012 | BAR | Lough | Promoted to active roster | | | Before |
| 8/18/2012 | GAR | Ross,T | Promoted to active roster | | | Before |
| 8/18/2012 | TEW | Billingsley | Placed on Injured List | | 8/18/2012 | Before |
| 8/18/2012 | TEW | Estrada | Promoted to active roster | | | Before |
| 8/20/2012 | ALP | Brothers | Demoted to reserve roster | | | Before |
| 8/20/2012 | ALP | Lowrie | Demoted to reserve roster | | | Before |
| 8/20/2012 | ALP | McDonald,Jo | Promoted to active roster | | | Before |
| 8/20/2012 | ALP | Wright,W | Promoted to active roster | | | Before |
| 8/20/2012 | BAR | Alvarez,H | Promoted to active roster | | | Before |
| 8/20/2012 | BAR | Wainwright | Demoted to reserve roster | | | Before |
| 8/20/2012 | CEN | Fien | Demoted to reserve roster | | | Before |
| 8/20/2012 | CEN | Wright,J | Promoted to active roster | | | Before |
| 8/20/2012 | GAR | Broxton | Promoted to active roster | | | Before |
| 8/20/2012 | GAR | Cecil | Demoted to reserve roster | | | Before |
| 8/20/2012 | GAR | McGee | Demoted to reserve roster | | | Before |
| 8/20/2012 | GAR | Richards | Promoted to active roster | | | Before |
| 8/21/2012 | ALP | Castillo,W | Promoted to active roster | | | Before |
| 8/21/2012 | ALP | Craig | Demoted to reserve roster | | | Before |
| 8/21/2012 | NEP | Morrow | Promoted to active roster | | | Before |
| 8/21/2012 | NEP | Quintana | Demoted to reserve roster | | | Before |
| 8/22/2012 | DLM | Millwood | Placed on Injured List | | 8/22/2012 | Before |
| 8/22/2012 | DLM | Richard | Promoted to active roster | | | Before |
| 8/23/2012 | GAR | Calhoun | Demoted to reserve roster | | | Before |
| 8/23/2012 | GAR | Grandal | Promoted to active roster | | | Before |
| 8/24/2012 | ALP | Colon,B | Promoted to active roster | | | Before |
| 8/24/2012 | ALP | Mazzaro | Placed on Injured List | | 8/24/2012 | Before |
| 8/24/2012 | CIN | Ciriaco | Promoted to active roster | | | Before |
| 8/24/2012 | CIN | Ramirez,Al | Demoted to reserve roster | | | Before |
| 8/24/2012 | CTW | Davis,I | Demoted to reserve roster | | | Before |
| 8/24/2012 | CTW | Diamond | Promoted to active roster | | | Before |
| 8/24/2012 | CTW | Kemp | Activated from Injured List | | | Before |
| 8/24/2012 | CTW | Peralta,W | Demoted to reserve roster | | | Before |
| 8/25/2012 | GAR | Gee | Promoted to active roster | | | Before |
| 8/25/2012 | GAR | Richards | Demoted to reserve roster | | | Before |
| 8/25/2012 | NEP | Belisario | Promoted to active roster | | | Before |
| 8/25/2012 | NEP | Byrdak | Demoted to reserve roster | | | Before |
| 8/25/2012 | NEP | Colvin | Promoted to active roster | | | Before |
| 8/25/2012 | NEP | Quentin | Placed on Injured List | | 8/25/2012 | Before |
| 8/25/2012 | NEP | Viciedo | Promoted to active roster | | | Before |
| 8/25/2012 | NEP | Willingham | Placed on Injured List | | 8/25/2012 | Before |
| 8/26/2012 | CIN | Arroyo | Promoted to active roster | | | Before |
| 8/26/2012 | CIN | Pettitte | Placed on Injured List | | 8/26/2012 | Before |
| 8/26/2012 | CTW | Betemit | Promoted to active roster | | | Before |
| 8/26/2012 | CTW | Rosario,W | Demoted to reserve roster | | | Before |
| 8/26/2012 | CTW | Sappelt | Demoted to reserve roster | | | Before |
| 8/26/2012 | CTW | Sappelt | Promoted to active roster | | | Before |
| 8/28/2012 | ALP | Craig | Promoted to active roster | | | Before |
| 8/28/2012 | ALP | Denorfia | Placed on Injured List | | 8/28/2012 | Before |
| 8/28/2012 | CEN | Carlin | Demoted to reserve roster | | | Before |
| 8/28/2012 | CEN | Montero,J | Promoted to active roster | | | Before |
| 8/28/2012 | CIN | Crisp | Promoted to active roster | | | Before |
| 8/28/2012 | CIN | Fowler | Demoted to reserve roster | | | Before |
| 8/31/2012 | ALP | Maholm | Promoted to active roster | | | Before |
| 8/31/2012 | ALP | Shaw | Demoted to reserve roster | | | Before |
| 8/31/2012 | CEN | Fuld | Promoted to active roster | | | Before |
| 8/31/2012 | CEN | Longoria | Demoted to reserve roster | | | Before |
| 8/31/2012 | DLM | Lucroy | Demoted to reserve roster | | | Before |
| 8/31/2012 | DLM | Recker,A | Promoted to active roster | | | Before |
| 8/31/2012 | NEP | Byrdak | Promoted to active roster | | | Before |
| 8/31/2012 | NEP | Peralta,Jo | Demoted to reserve roster | | | Before |
| 9/1/2012 | ALP | Brothers | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Donaldson | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Ellsbury | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Federowicz | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Fister | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Jones,C | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Lind | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Lowrie | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Machi | Promoted to active roster | | | Before |
| 9/1/2012 | ALP | Teagarden | Promoted to active roster | | | Before |
| 9/1/2012 | BAR | Alvarez,H | Demoted to reserve roster | | | Before |
| 9/1/2012 | BAR | Corbin | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Amarista,A | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Carrera | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Dominguez | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Griffin | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Lewis,C | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Maldonado,M | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Niemann | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Oliver | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Valdes,R | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Veal | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Wilson,CJ | Promoted to active roster | | | Before |
| 9/1/2012 | BBG | Zambrano | Promoted to active roster | | | Before |
| 9/1/2012 | CEN | Deduno | Promoted to active roster | | | Before |
| 9/1/2012 | CEN | Gaudin | Promoted to active roster | | | Before |
| 9/1/2012 | CEN | Guerrier | Promoted to active roster | | | Before |
| 9/1/2012 | CEN | Olivo | Promoted to active roster | | | Before |
| 9/1/2012 | CEN | Sanchez,H | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Allen,C | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Berry | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Callaspo | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Frandsen | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Gonzalez,G | Activated from Injured List | | | Before |
| 9/1/2012 | CIN | Konerko | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Kottaras,G | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Miller,A | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Moore,T | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Morse | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Perez,O | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Perkins | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Ramirez,Al | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Storen | Promoted to active roster | | | Before |
| 9/1/2012 | CIN | Valbuena | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Anderson,BF | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Bourjos | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Buchholz | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Corporan | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Davis,I | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Fiers | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Inge,B | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Iwakuma | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Kimbrel | Demoted to reserve roster | | | Before |
| 9/1/2012 | CTW | Lyon,B | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | O'Day | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Phelps,D | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Sappelt | Promoted to active roster | | | Before |
| 9/1/2012 | CTW | Soriano,R | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Ankiel | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Arrieta | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Bonifacio | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Carpenter,M | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Cecil | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Duda | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Duke | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Dyson,J | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Garcia,F | Activated from Injured List | | | Before |
| 9/1/2012 | GAR | Holt | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Manship | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Sipp | Promoted to active roster | | | Before |
| 9/1/2012 | GAR | Van Slyke | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Archer | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Arredondo | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Bass | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Cooper | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Ford | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Garza | Demoted to reserve roster | | | Before |
| 9/1/2012 | TEW | Garza | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Layne | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Lobaton | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Markakis | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Martinez,C | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Mattheus | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Moreland | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Nelson | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Parnell | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Satin | Promoted to active roster | | | Before |
| 9/1/2012 | TEW | Vogt | Promoted to active roster | | | Before |
| 9/2/2012 | ALP | Ogando | Demoted to reserve roster | | | Before |
| 9/2/2012 | NEP | Baxter | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Detwiler | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Iannetta | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Kubel | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | LaHair | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Nieves,W | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Parker,J | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Quintana | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Russell | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Thayer | Promoted to active roster | | | Before |
| 9/2/2012 | NEP | Uggla | Promoted to active roster | | | Before |
| 9/4/2012 | BAR | Feldman | Demoted to reserve roster | | | Before |
| 9/4/2012 | BAR | Otero | Promoted to active roster | | | Before |
| 9/4/2012 | BBG | Jansen | Demoted to reserve roster | | | Before |
| 9/4/2012 | BBG | Weaver | Demoted to reserve roster | | | Before |
| 9/5/2012 | DLM | Blanco,H | Demoted to reserve roster | | | Before |
| 9/5/2012 | DLM | Shoppach | Promoted to active roster | | | Before |
| 9/5/2012 | GAR | Duke | Demoted to reserve roster | | | Before |
| 9/5/2012 | GAR | Huff,A | Demoted to reserve roster | | | Before |
| 9/5/2012 | GAR | Manship | Demoted to reserve roster | | | Before |
| 9/6/2012 | BBG | Horst | Demoted to reserve roster | | | Before |
| 9/6/2012 | DLM | Millwood | Activated from Injured List | | | Before |
| 9/7/2012 | ALP | Ziegler | Demoted to reserve roster | | | Before |
| 9/7/2012 | BAR | Bloomquist | Demoted to reserve roster | | | Before |
| 9/7/2012 | BAR | Corbin | Demoted to reserve roster | | | Before |
| 9/7/2012 | BAR | Cruz,N | Promoted to active roster | | | Before |
| 9/7/2012 | BAR | Lough | Demoted to reserve roster | | | Before |
| 9/7/2012 | BAR | Martinez,JD | Promoted to active roster | | | Before |
| 9/7/2012 | BAR | Martinez,Lu | Promoted to active roster | | | Before |
| 9/7/2012 | BAR | Miller,S | Promoted to active roster | | | Before |
| 9/7/2012 | BAR | Scheppers | Demoted to reserve roster | | | Before |
| 9/7/2012 | CIN | Cespedes | Demoted to reserve roster | | | Before |
| 9/7/2012 | CIN | Martin,L | Promoted to active roster | | | Before |
| 9/7/2012 | DLM | Millwood | Demoted to reserve roster | | | Before |
| 9/7/2012 | GAR | Morneau | Demoted to reserve roster | | | Before |
| 9/8/2012 | BAR | Adams,Ma | Demoted to reserve roster | | | Before |
| 9/8/2012 | BAR | Alvarez,H | Promoted to active roster | | | Before |
| 9/8/2012 | BAR | Brown,D | Demoted to reserve roster | | | Before |
| 9/8/2012 | BAR | Byrd,M | Demoted to reserve roster | | | Before |
| 9/8/2012 | BAR | Cruz,T | Promoted to active roster | | | Before |
| 9/8/2012 | BAR | Murphy,DM | Promoted to active roster | | | Before |
| 9/8/2012 | BAR | Rizzo | Promoted to active roster | | | Before |
| 9/8/2012 | BAR | Ruf | Demoted to reserve roster | | | Before |
| 9/8/2012 | DLM | Britton | Promoted to active roster | | | Before |
| 9/8/2012 | DLM | Lowe,M | Demoted to reserve roster | | | Before |
| 9/8/2012 | GAR | Ross,T | Demoted to reserve roster | | | Before |
| 9/8/2012 | NEP | Boggs | Demoted to reserve roster | | | Before |
| 9/8/2012 | TEW | Patton | Demoted to reserve roster | | | Before |
| 9/9/2012 | ALP | Mazzaro | Activated from Injured List | | | Before |
| 9/9/2012 | NEP | Peralta,Jo | Promoted to active roster | | | Before |
| 9/9/2012 | NEP | Quentin | Activated from Injured List | | | Before |
| 9/9/2012 | NEP | Willingham | Activated from Injured List | | | Before |
| 9/9/2012 | TEW | Johnson,Ji | Demoted to reserve roster | | | Before |
| 9/10/2012 | GAR | Broxton | Demoted to reserve roster | | | Before |
| 9/10/2012 | TEW | Hoover | Demoted to reserve roster | | | Before |
| 9/13/2012 | ALP | Castillo,W | Demoted to reserve roster | | | Before |
| 9/13/2012 | ALP | Denorfia | Activated from Injured List | | | Before |
| 9/13/2012 | TEW | Satin | Demoted to reserve roster | | | Before |
| 9/14/2012 | ALP | Machi | Demoted to reserve roster | | | Before |
| 9/14/2012 | CTW | Lopez,W | Demoted to reserve roster | | | Before |
| 9/14/2012 | DLM | Bumgarner | Demoted to reserve roster | | | Before |
| 9/14/2012 | DLM | Chen,W | Demoted to reserve roster | | | Before |
| 9/14/2012 | DLM | Duensing | Promoted to active roster | | | Before |
| 9/14/2012 | DLM | Millwood | Promoted to active roster | | | Before |
| 9/14/2012 | DLM | Qualls,C | Promoted to active roster | | | Before |
| 9/14/2012 | DLM | Scherzer | Promoted to active roster | | | Before |
| 9/14/2012 | GAR | Duda | Demoted to reserve roster | | | Before |
| 9/14/2012 | NEP | Belisario | Demoted to reserve roster | | | Before |
| 9/14/2012 | NEP | Carter | Demoted to reserve roster | | | Before |
| 9/14/2012 | NEP | Miley | Demoted to reserve roster | | | Before |
| 9/15/2012 | DLM | Bumgarner | Promoted to active roster | | | Before |
| 9/15/2012 | DLM | Chen,W | Promoted to active roster | | | Before |
| 9/15/2012 | DLM | Frasor | Promoted to active roster | | | Before |
| 9/15/2012 | GAR | McGee | Promoted to active roster | | | Before |
| 9/15/2012 | GAR | Neshek | Promoted to active roster | | | Before |
| 9/15/2012 | GAR | Turner,Ju | Promoted to active roster | | | Before |
| 9/16/2012 | ALP | Colon,B | Demoted to reserve roster | | | Before |
| 9/16/2012 | ALP | Ogando | Promoted to active roster | | | Before |
| 9/16/2012 | BAR | Miller,S | Demoted to reserve roster | | | Before |
| 9/16/2012 | GAR | Cecil | Demoted to reserve roster | | | Before |
| 9/16/2012 | TEW | Janssen,C | Demoted to reserve roster | | | Before |
| 9/17/2012 | CEN | Dickey | Demoted to reserve roster | | | Before |
| 9/17/2012 | CIN | Iglesias | Promoted to active roster | | | Before |
| 9/17/2012 | CIN | Santana,C | Demoted to reserve roster | | | Before |
| 9/17/2012 | NEP | Jaso | Demoted to reserve roster | | | Before |
| 9/17/2012 | NEP | Morrow | Demoted to reserve roster | | | Before |
| 9/17/2012 | TEW | Archer | Demoted to reserve roster | | | Before |
| 9/17/2012 | TEW | Billingsley | Activated from Injured List | | | Before |
| 9/18/2012 | GAR | Neshek | Demoted to reserve roster | | | Before |
| 9/19/2012 | ALP | Federowicz | Demoted to reserve roster | | | Before |
| 9/19/2012 | CTW | Kimbrel | Promoted to active roster | | | Before |
| 9/19/2012 | GAR | Carpenter,M | Demoted to reserve roster | | | Before |
| 9/20/2012 | BBG | Marshall | Demoted to reserve roster | | | Before |
| 9/20/2012 | CEN | Trout | Demoted to reserve roster | | | Before |
| 9/20/2012 | CTW | Kimbrel | Demoted to reserve roster | | | Before |
| 9/20/2012 | CTW | Tazawa | Demoted to reserve roster | | | Before |
| 9/20/2012 | DLM | Britton | Demoted to reserve roster | | | Before |
| 9/20/2012 | TEW | McDonald,Ja | Demoted to reserve roster | | | Before |
| 9/22/2012 | BAR | Hill,R | Demoted to reserve roster | | | Before |
| 9/22/2012 | CTW | Desmond | Demoted to reserve roster | | | Before |
| 9/22/2012 | CTW | Fiers | Demoted to reserve roster | | | Before |
| 9/22/2012 | CTW | Hudson,T | Demoted to reserve roster | | | Before |
| 9/22/2012 | CTW | Rodney | Demoted to reserve roster | | | Before |
| 9/22/2012 | CTW | Verlander | Demoted to reserve roster | | | Before |
| 9/22/2012 | CTW | Wright,D | Demoted to reserve roster | | | Before |
| 9/23/2012 | BAR | Abad | Promoted to active roster | | | Before |
| 9/23/2012 | BAR | Cobb | Promoted to active roster | | | Before |
| 9/23/2012 | BAR | Coleman,L | Promoted to active roster | | | Before |
| 9/23/2012 | BAR | Otero | Demoted to reserve roster | | | Before |
| 9/23/2012 | CIN | Sanchez,A | Demoted to reserve roster | | | Before |
| 9/23/2012 | GAR | Brach | Promoted to active roster | | | Before |
| 9/23/2012 | GAR | McGee | Demoted to reserve roster | | | Before |
| 9/23/2012 | NEP | Peavy | Demoted to reserve roster | | | Before |
| 9/23/2012 | TEW | Gonzalez,C | Demoted to reserve roster | | | Before |
| 9/25/2012 | ALP | Tolleson,St | Demoted to reserve roster | | | Before |
| 9/25/2012 | BAR | Pedroia | Demoted to reserve roster | | | Before |
| 9/25/2012 | BAR | Rutledge | Signed | | | Before |
| 9/25/2012 | CEN | Harrell | Demoted to reserve roster | | | Before |
| 9/25/2012 | GAR | Negron | Promoted to active roster | | | Before |
| 9/25/2012 | GAR | Nieuwenhuis | Demoted to reserve roster | | | Before |
| 9/25/2012 | NEP | Freese | Demoted to reserve roster | | | Before |
| 9/25/2012 | TEW | Collmenter | Demoted to reserve roster | | | Before |
| 9/26/2012 | CEN | Rios | Demoted to reserve roster | | | Before |
| 9/26/2012 | CEN | Sabathia | Demoted to reserve roster | | | Before |
| 9/26/2012 | GAR | Turner,Ju | Demoted to reserve roster | | | Before |
| 9/27/2012 | CIN | Santana,C | Promoted to active roster | | | Before |
| 9/27/2012 | GAR | Negron | Demoted to reserve roster | | | Before |
| 9/27/2012 | GAR | Richards | Promoted to active roster | | | Before |
| 9/27/2012 | GAR | Sipp | Demoted to reserve roster | | | Before |
| 9/28/2012 | BBG | McCutchen,A | Demoted to reserve roster | | | Before |
| 9/28/2012 | CIN | Cueto | Demoted to reserve roster | | | Before |
| 9/28/2012 | DLM | Blanco,H | Promoted to active roster | | | Before |
| 9/28/2012 | DLM | Bumgarner | Demoted to reserve roster | | | Before |
| 9/28/2012 | GAR | McKenry | Demoted to reserve roster | | | Before |
| 9/28/2012 | NEP | Breslow,C | Demoted to reserve roster | | | Before |
| 9/28/2012 | NEP | Byrdak | Demoted to reserve roster | | | Before |
| 9/29/2012 | ALP | Ogando | Demoted to reserve roster | | | Before |
| 9/29/2012 | BAR | Happ,JA | Promoted to active roster | | | Before |
| 9/29/2012 | BAR | Mikolas | Demoted to reserve roster | | | Before |
| 9/29/2012 | BAR | Ruf | Promoted to active roster | | | Before |
| 9/29/2012 | BBG | Bautista | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Dempster | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Gimenez,H | Promoted to active roster | | | Before |
| 9/29/2012 | BBG | Griffin | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Johnson,S | Promoted to active roster | | | Before |
| 9/29/2012 | BBG | Keppinger | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Lewis,C | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Niemann | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Reimold | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Ruggiano | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Valdes,R | Demoted to reserve roster | | | Before |
| 9/29/2012 | BBG | Veal | Promoted to active roster | | | Before |
| 9/29/2012 | GAR | Arrieta | Demoted to reserve roster | | | Before |
| 9/29/2012 | GAR | Castro,S | Demoted to reserve roster | | | Before |
| 9/29/2012 | GAR | Van Slyke | Demoted to reserve roster | | | Before |
| 9/29/2012 | NEP | Jackson,A | Demoted to reserve roster | | | Before |
| 9/30/2012 | ALP | Fister | Demoted to reserve roster | | | Before |
| 9/30/2012 | BAR | Walden | Demoted to reserve roster | | | Before |
| 9/30/2012 | CIN | Simon | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Anderson,BF | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Betemit | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Bourjos | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Buchholz | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Corporan | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Desmond | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Diamond | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Fiers | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Hudson,T | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Inge,B | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Iwakuma | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Kimbrel | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Lopez,W | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Loup | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Lyon,B | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Moss | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Motte | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | O'Day | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Peralta,W | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Peralta,W | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Peralta,W | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Phelps,D | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Ramirez,Er | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Rodney | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Rosario,W | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Sappelt | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Soriano,R | Demoted to reserve roster | | | Before |
| 9/30/2012 | CTW | Tazawa | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Verlander | Promoted to active roster | | | Before |
| 9/30/2012 | CTW | Wright,D | Promoted to active roster | | | Before |
| 9/30/2012 | DLM | Norberto | Demoted to reserve roster | | | Before |
| 9/30/2012 | DLM | Pestano | Demoted to reserve roster | | | Before |
| 9/30/2012 | DLM | Rapada | Demoted to reserve roster | | | Before |
| 9/30/2012 | NEP | Rauch | Demoted to reserve roster | | | Before |