| Transactions |
| Date | Team | Player | Type | OthTm | EffDate | When |
| 4/11/1955 | Bal | Pillette | Placed on disabled list |   |   | Before |
| 4/11/1955 | Bos | Williams | Retired |   |   | Before |
| 4/13/1955 | Cin | Hooper | Acquired via trade | Cle |   | Before |
| 4/13/1955 | NYA | Martin | Placed on restricted list |   |   | Before |
| 4/14/1955 | Bal | Wilson | Acquired via trade | Mil |   | Before |
| 4/14/1955 | Bos | Bolling | Placed on disabled list |   |   | Before |
| 4/15/1955 | NYA | Noren | Suspended |   |   | Before |
| 4/16/1955 | ChA | Merriman | Traded away | ChN |   | Before |
| 4/16/1955 | ChN | Merriman | Acquired via trade | ChA |   | Before |
| 4/17/1955 | Brk | Moryn | Demoted to reserve roster |   |   | Before |
| 4/17/1955 | Phi | Micelotta | Demoted to reserve roster |   |   | Before |
| 4/17/1955 | Phi | Westlake | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | Bal | Leppert | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | Bal | Stephens | Released |   |   | Before |
| 4/18/1955 | Cin | Fisher | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | NYA | Noren | Reinstated |   |   | Before |
| 4/18/1955 | Pit | Bell | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | Pit | Hall | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | Pit | Thies | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | StL | Jacobs | Demoted to reserve roster |   |   | Before |
| 4/18/1955 | Was | Gonzales | Released |   |   | Before |
| 4/19/1955 | StL | Raschi | Released |   |   | Before |
| 4/20/1955 | Bos | Consolo | Demoted to reserve roster |   |   | Before |
| 4/22/1955 | KC | MacKenzie | Promoted to active roster |   |   | Before |
| 4/22/1955 | NYA | Coleman | Placed on disabled list |   |   | After |
| 4/24/1955 | NYN | Spencer | Demoted to reserve roster |   |   | Before |
| 4/26/1955 | Mil | Gorin | Demoted to reserve roster |   |   | Before |
| 4/27/1955 | Det | Belardi | Demoted to reserve roster |   |   | Before |
| 4/27/1955 | Phi | Greenwood | Demoted to reserve roster |   |   | Before |
| 4/27/1955 | Phi | Schell | Demoted to reserve roster |   |   | Before |
| 4/28/1955 | KC | Raschi | Signed |   |   | Before |
| 4/28/1955 | KC | Sleater | Acquired via trade | NYA |   | Before |
| 4/28/1955 | KC | Stewart | Demoted to reserve roster |   |   | Before |
| 4/28/1955 | KC | Van Brabant | Demoted to reserve roster |   |   | Before |
| 4/28/1955 | KC | Wheat | Demoted to reserve roster |   |   | Before |
| 4/30/1955 | Brk | Bessent | Demoted to reserve roster |   |   | Before |
| 4/30/1955 | Brk | Hamric | Demoted to reserve roster |   |   | Before |
| 4/30/1955 | Cin | Burgess | Acquired via trade | Phi |   | Before |
| 4/30/1955 | Cin | Gorbous | Traded away | Phi |   | Before |
| 4/30/1955 | Cin | Greengrass | Traded away | Phi |   | Before |
| 4/30/1955 | Cin | Palys | Acquired via trade | Phi |   | Before |
| 4/30/1955 | Cin | Ridzik | Acquired via trade | Phi |   | Before |
| 4/30/1955 | Cin | Seminick | Traded away | Phi |   | Before |
| 4/30/1955 | KC | Blackwell | Released |   |   | Before |
| 4/30/1955 | KC | MacKenzie | Demoted to reserve roster |   |   | Before |
| 4/30/1955 | Phi | Bowman | Demoted to reserve roster |   |   | Before |
| 4/30/1955 | Phi | Burgess | Traded away | Cin |   | Before |
| 4/30/1955 | Phi | Gorbous | Acquired via trade | Cin |   | Before |
| 4/30/1955 | Phi | Greengrass | Acquired via trade | Cin |   | Before |
| 4/30/1955 | Phi | Kazanski | Demoted to reserve roster |   |   | Before |
| 4/30/1955 | Phi | Palys | Traded away | Cin |   | Before |
| 4/30/1955 | Phi | Ridzik | Traded away | Cin |   | Before |
| 4/30/1955 | Phi | Seminick | Acquired via trade | Cin |   | Before |
| 4/30/1955 | Phi | Smalley | Acquired via trade | Mil |   | Before |
| 5/1/1955 | ChN | Wade | Demoted to reserve roster |   |   | Before |
| 5/1/1955 | ChN | Morgan | Demoted to reserve roster |   |   | After |
| 5/2/1955 | ChA | Stephens | Signed |   |   | Before |
| 5/2/1955 | Det | Black | Demoted to reserve roster |   |   | Before |
| 5/2/1955 | Det | Froats | Demoted to reserve roster |   |   | Before |
| 5/2/1955 | Det | Schultz | Demoted to reserve roster |   |   | Before |
| 5/2/1955 | Pit | Roberts | Demoted to reserve roster |   |   | Before |
| 5/2/1955 | Pit | Smith,D | Demoted to reserve roster |   |   | Before |
| 5/2/1955 | Pit | Smith,E | Demoted to reserve roster |   |   | Before |
| 5/3/1955 | KC | Bevan | Demoted to reserve roster |   |   | Before |
| 5/3/1955 | KC | Trice | Demoted to reserve roster |   |   | Before |
| 5/5/1955 | Brk | Newcombe | Suspended |   |   | Before |
| 5/6/1955 | Brk | Newcombe | Reinstated |   |   | Before |
| 5/9/1955 | Bal | Maxwell | Traded away | Det |   | Before |
| 5/9/1955 | Brk | Koufax | Placed on disabled list |   |   | Before |
| 5/9/1955 | ChN | Amor | Demoted to reserve roster |   |   | Before |
| 5/9/1955 | ChN | Church | Demoted to reserve roster |   |   | Before |
| 5/9/1955 | ChN | Fanning | Demoted to reserve roster |   |   | Before |
| 5/9/1955 | ChN | Hillman | Demoted to reserve roster |   |   | Before |
| 5/9/1955 | ChN | Tappe,E | Demoted to reserve roster |   |   | Before |
| 5/9/1955 | ChN | Thorpe | Demoted to reserve roster |   |   | Before |
| 5/9/1955 | Det | Maxwell | Acquired via trade | Bal |   | Before |
| 5/10/1955 | Bal | Coleman | Placed on disabled list |   |   | Before |
| 5/10/1955 | Bos | Brown | Released |   |   | Before |
| 5/10/1955 | Bos | Freeman | Traded away | Cin |   | Before |
| 5/11/1955 | Bal | Alexander | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Bal | Ferrarese | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Bal | Pillette | Activated from disabled list |   |   | Before |
| 5/11/1955 | Bal | Schallock | Acquired via trade | NYA |   | After |
| 5/11/1955 | Bos | Friend | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Bos | Smith | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Bos | Trimble | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | ChA | Cavarretta | Released |   |   | Before |
| 5/11/1955 | ChA | Gray | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | ChA | Jok | Released |   |   | Before |
| 5/11/1955 | ChN | Lary | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Cin | Baczewski | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Cin | Bailey | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Cin | Freeman | Acquired via trade | Bos |   | Before |
| 5/11/1955 | Cin | Lane | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Cin | Pearce | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Cle | Altobelli | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Cle | Newhouser | Released |   |   | Before |
| 5/11/1955 | Cle | Simpson | Traded away | KC |   | Before |
| 5/11/1955 | Det | Souchock | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Bishop | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Bollweg | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Burtschy | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Dixon | Traded away | NYA |   | Before |
| 5/11/1955 | KC | Fricano | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Gray | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Herbert | Acquired via trade | Det |   | Before |
| 5/11/1955 | KC | Jacobs | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Lopez | Promoted to active roster |   |   | Before |
| 5/11/1955 | KC | Portocarrero | Placed on disabled list |   |   | Before |
| 5/11/1955 | KC | Robertson | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | KC | Simpson | Acquired via trade | Cle |   | Before |
| 5/11/1955 | KC | Sain | Acquired via trade | NYA |   | After |
| 5/11/1955 | KC | Slaughter | Acquired via trade | NYA |   | After |
| 5/11/1955 | Mil | Crone | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | NYA | Larsen | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | NYA | Sain | Traded away | KC |   | After |
| 5/11/1955 | NYA | Schallock | Traded away | Bal |   | After |
| 5/11/1955 | NYA | Slaughter | Traded away | KC |   | After |
| 5/11/1955 | NYN | Grasso | Released |   |   | Before |
| 5/11/1955 | Phi | Baker | Released |   |   | Before |
| 5/11/1955 | Phi | Clark | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Phi | Owens | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Pit | Grunwald | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Pit | Peterson | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | StL | Alston | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | StL | Wooldridge | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Was | Currie | Demoted to reserve roster |   |   | Before |
| 5/11/1955 | Was | Hyde | Demoted to reserve roster |   |   | Before |
| 5/13/1955 | Bal | Miller | Demoted to reserve roster |   |   | Before |
| 5/13/1955 | Det | Samford | Demoted to reserve roster |   |   | Before |
| 5/16/1955 | Cin | Hooper | Demoted to reserve roster |   |   | Before |
| 5/16/1955 | Was | Snyder | Demoted to reserve roster |   |   | Before |
| 5/19/1955 | ChA | Minoso | Placed on disabled list |   |   | Before |
| 5/23/1955 | Bal | Kuzava | Traded away | Phi |   | Before |
| 5/23/1955 | NYN | Castleman | Demoted to reserve roster |   |   | Before |
| 5/23/1955 | NYN | Gordon | Acquired via trade | Pit |   | Before |
| 5/23/1955 | Phi | Kuzava | Acquired via trade | Bal |   | Before |
| 5/23/1955 | Phi | Lovenguth | Demoted to reserve roster |   |   | Before |
| 5/23/1955 | Pit | Bowman | Demoted to reserve roster |   |   | Before |
| 5/23/1955 | Pit | Gordon | Traded away | NYN |   | Before |
| 5/23/1955 | Was | Levan | Demoted to reserve roster |   |   | Before |
| 5/27/1955 | Bos | Kemmerer | Demoted to reserve roster |   |   | Before |
| 5/28/1955 | Bos | Williams | Came out of retirement |   |   | Before |
| 5/28/1955 | StL | Walker | Signed |   |   | Before |
| 5/29/1955 | ChN | Tappe,T | Placed on disabled list |   |   | After |
| 5/29/1955 | Was | Schoonmaker | Signed |   |   | Before |
| 5/30/1955 | Bal | Kennedy | Traded away | ChA |   | Before |
| 5/30/1955 | ChA | Esposito | Demoted to reserve roster |   |   | Before |
| 5/30/1955 | ChA | Kennedy | Acquired via trade | Bal |   | Before |
| 5/30/1955 | ChA | McGhee | Demoted to reserve roster |   |   | Before |
| 5/30/1955 | Cin | Valentine | Demoted to reserve roster |   |   | Before |
| 5/30/1955 | Pit | Peterson | Promoted to active roster |   |   | Before |
| 5/31/1955 | KC | Boyer,Cle | Signed |   |   | Before |
| 5/31/1955 | KC | Suder | Released |   |   | Before |
| 5/31/1955 | Mil | Edelman | Signed |   |   | Before |
| 5/31/1955 | StL | Schofield | Demoted to reserve roster |   |   | Before |
| 6/1/1955 | Bal | Marsh | Placed on disabled list |   |   | Before |
| 6/1/1955 | KC | Harrington | Promoted to active roster |   |   | Before |
| 6/2/1955 | Det | Birrer | Promoted to active roster |   |   | Before |
| 6/2/1955 | Det | Fletcher | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | Det | Flowers | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | Det | Porter | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | Mil | Crone | Promoted to active roster |   |   | Before |
| 6/2/1955 | Mil | Pendleton | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | Mil | Robinson | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | NYN | Corwin | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | NYN | Gardner | Demoted to reserve roster |   |   | Before |
| 6/2/1955 | NYN | Harris | Promoted to active roster |   |   | Before |
| 6/2/1955 | NYN | Monzant | Promoted to active roster |   |   | Before |
| 6/3/1955 | Cin | Silvera | Signed |   |   | Before |
| 6/3/1955 | Mil | Rice | Acquired via trade | StL |   | Before |
| 6/3/1955 | Mil | White | Demoted to reserve roster |   |   | Before |
| 6/3/1955 | StL | Burbrink | Promoted to active roster |   |   | Before |
| 6/3/1955 | StL | Rice | Traded away | Mil |   | Before |
| 6/3/1955 | StL | Whisenant | Promoted to active roster |   |   | Before |
| 6/4/1955 | Bal | Causey | Signed |   |   | Before |
| 6/4/1955 | ChA | Minoso | Activated from disabled list |   |   | Before |
| 6/6/1955 | Bal | Dorish | Acquired via trade | ChA |   | Before |
| 6/6/1955 | Bal | Moss | Traded away | ChA |   | Before |
| 6/6/1955 | ChA | Dorish | Traded away | Bal |   | Before |
| 6/6/1955 | ChA | Moss | Acquired via trade | Bal |   | Before |
| 6/6/1955 | ChN | Cohen | Demoted to reserve roster |   |   | Before |
| 6/6/1955 | ChN | Hillman | Promoted to active roster |   |   | Before |
| 6/7/1955 | Bal | Kretlow | Demoted to reserve roster |   |   | Before |
| 6/7/1955 | ChA | Busby | Acquired via trade | Was |   | Before |
| 6/7/1955 | ChA | Chakales | Traded away | Was |   | Before |
| 6/7/1955 | ChA | Courtney | Traded away | Was |   | Before |
| 6/7/1955 | ChA | Groth | Traded away | Was |   | Before |
| 6/7/1955 | ChA | Howell | Promoted to active roster |   |   | Before |
| 6/7/1955 | Phi | Negray | Acquired via trade | Brk |   | Before |
| 6/7/1955 | Was | Busby | Traded away | ChA |   | Before |
| 6/7/1955 | Was | Chakales | Acquired via trade | ChA |   | Before |
| 6/7/1955 | Was | Courtney | Acquired via trade | ChA |   | Before |
| 6/7/1955 | Was | Groth | Acquired via trade | ChA |   | Before |
| 6/8/1955 | Brk | Koufax | Activated from disabled list |   |   | Before |
| 6/8/1955 | Brk | Lasorda | Demoted to reserve roster |   |   | Before |
| 6/9/1955 | Brk | Black | Traded away | Cin |   | Before |
| 6/9/1955 | ChA | Powell | Signed |   |   | Before |
| 6/9/1955 | Cin | Black | Acquired via trade | Brk |   | Before |
| 6/9/1955 | Was | Stewart | Demoted to reserve roster |   |   | Before |
| 6/11/1955 | Bal | Coleman | Activated from disabled list |   |   | Before |
| 6/11/1955 | Det | Cristante | Demoted to reserve roster |   |   | Before |
| 6/11/1955 | Det | Small | Signed |   |   | Before |
| 6/11/1955 | KC | Kryhoski | Demoted to reserve roster |   |   | Before |
| 6/11/1955 | KC | Portocarrero | Activated from disabled list |   |   | Before |
| 6/14/1955 | Brk | Borkowski | Acquired via trade | Cin |   | Before |
| 6/14/1955 | Cin | Borkowski | Traded away | Brk |   | Before |
| 6/15/1955 | Bal | Byrd | Traded away | ChA |   | Before |
| 6/15/1955 | Bal | Cox | Retired |   |   | Before |
| 6/15/1955 | Bal | Pope | Acquired via trade | Cle |   | Before |
| 6/15/1955 | Bal | Westlake | Acquired via trade | Cle |   | Before |
| 6/15/1955 | Bal | Woodling | Traded away | Cle |   | Before |
| 6/15/1955 | ChA | Byrd | Acquired via trade | Bal |   | Before |
| 6/15/1955 | ChA | Gray | Released |   |   | Before |
| 6/15/1955 | ChA | Marshall | Placed on disabled list |   |   | After |
| 6/15/1955 | ChN | Friend | Promoted to active roster |   |   | Before |
| 6/15/1955 | Cle | Gray | Signed |   |   | Before |
| 6/15/1955 | Cle | Pope | Traded away | Bal |   | Before |
| 6/15/1955 | Cle | Westlake | Traded away | Bal |   | Before |
| 6/15/1955 | Cle | Woodling | Acquired via trade | Bal |   | Before |
| 6/15/1955 | Det | Torgeson | Acquired via trade | Phi |   | Before |
| 6/15/1955 | Phi | Easton | Promoted to active roster |   |   | Before |
| 6/15/1955 | Phi | Torgeson | Traded away | Det |   | Before |
| 6/15/1955 | Pit | Donoso | Promoted to active roster |   |   | Before |
| 6/15/1955 | Pit | Freese,Go | Demoted to reserve roster |   |   | Before |
| 6/15/1955 | Pit | O'Brien,E | Promoted to active roster |   |   | Before |
| 6/15/1955 | Pit | O'Brien,J | Promoted to active roster |   |   | Before |
| 6/15/1955 | Pit | Wade | Demoted to reserve roster |   |   | Before |
| 6/15/1955 | StL | Moford | Demoted to reserve roster |   |   | Before |
| 6/15/1955 | StL | Schultz | Demoted to reserve roster |   |   | Before |
| 6/15/1955 | StL | Wooldridge | Promoted to active roster |   |   | Before |
| 6/15/1955 | StL | Wright | Promoted to active roster |   |   | Before |
| 6/16/1955 | Bos | Agganis | Placed on disabled list |   |   | Before |
| 6/16/1955 | Bos | Bolling | Activated from disabled list |   |   | Before |
| 6/17/1955 | Bos | Pagliaroni | Signed |   |   | Before |
| 6/19/1955 | Bal | Waitkus | Placed on disabled list |   |   | Before |
| 6/20/1955 | Bal | Gastall | Signed |   |   | Before |
| 6/20/1955 | Bal | Nelson | Signed |   |   | Before |
| 6/20/1955 | Was | Oldis | Demoted to reserve roster |   |   | Before |
| 6/20/1955 | Was | Roig | Demoted to reserve roster |   |   | Before |
| 6/20/1955 | Was | Valdivielso | Promoted to active roster |   |   | Before |
| 6/21/1955 | Pit | Montemayor | Demoted to reserve roster |   |   | Before |
| 6/22/1955 | Cle | Locklin | Promoted to active roster |   |   | Before |
| 6/23/1955 | Bos | Mele | Traded away | Cin |   | Before |
| 6/23/1955 | Cin | Mele | Acquired via trade | Bos |   | Before |
| 6/23/1955 | Det | Miller | Demoted to reserve roster |   |   | Before |
| 6/24/1955 | NYN | Irvin | Demoted to reserve roster |   |   | Before |
| 6/24/1955 | NYN | Terwilliger | Promoted to active roster |   |   | Before |
| 6/24/1955 | Pit | King | Demoted to reserve roster |   |   | Before |
| 6/27/1955 | Bal | Majeski | Acquired via trade | Cle |   | Before |
| 6/27/1955 | Bal | Young | Traded away | Cle |   | Before |
| 6/27/1955 | Cle | Majeski | Traded away | Bal |   | Before |
| 6/27/1955 | Cle | Young | Acquired via trade | Bal |   | Before |
| 6/28/1955 | Brk | Meyer | Placed on disabled list |   |   | Before |
| 6/28/1955 | ChA | Johnson | Promoted to active roster |   |   | Before |
| 6/28/1955 | Cin | Podbielan | Placed on disabled list |   |   | Before |
| 6/28/1955 | Cle | Altobelli | Promoted to active roster |   |   | Before |
| 6/28/1955 | Det | Cristante | Promoted to active roster |   |   | Before |
| 6/28/1955 | Pit | Martin | Signed |   |   | Before |
| 6/28/1955 | Pit | Purkey | Demoted to reserve roster |   |   | Before |
| 6/29/1955 | Cin | Brovia | Signed |   |   | Before |
| 6/30/1955 | Cle | Gray | Released |   |   | Before |
| 6/30/1955 | NYA | Gray | Signed |   |   | Before |
| 7/1/1955 | Bal | Coleman | Released |   |   | Before |
| 7/1/1955 | Bal | Marsh | Activated from disabled list |   |   | Before |
| 7/1/1955 | Bal | Pyburn | Placed on disabled list |   |   | Before |
| 7/1/1955 | ChA | Stephens | Released |   |   | Before |
| 7/2/1955 | Bal | Philley | Acquired via trade | Cle |   | Before |
| 7/2/1955 | Cle | Kuhn | Signed |   |   | Before |
| 7/2/1955 | Cle | Philley | Traded away | Bal |   | Before |
| 7/3/1955 | Cin | Landrith | Placed on disabled list |   | 6/29/1955 | Before |
| 7/4/1955 | Bal | Hale | Promoted to active roster |   |   | Before |
| 7/4/1955 | Cin | Batts | Signed |   |   | Before |
| 7/6/1955 | Det | Fain | Released |   |   | Before |
| 7/8/1955 | Bal | Zuverink | Acquired via trade | Det |   | Before |
| 7/8/1955 | Det | Zuverink | Traded away | Bal |   | Before |
| 7/9/1955 | Bal | Rogovin | Released |   |   | Before |
| 7/9/1955 | Det | Coleman | Signed |   |   | Before |
| 7/9/1955 | Mil | Jay | Demoted to reserve roster |   |   | Before |
| 7/9/1955 | Mil | Paine | Promoted to active roster |   |   | Before |
| 7/9/1955 | Phi | Rogovin | Signed |   |   | Before |
| 7/11/1955 | Bal | Pillette | Demoted to reserve roster |   |   | Before |
| 7/11/1955 | Pit | Koback | Demoted to reserve roster |   |   | Before |
| 7/12/1955 | StL | Jones | Demoted to reserve roster |   |   | Before |
| 7/12/1955 | StL | Schmidt | Promoted to active roster |   |   | Before |
| 7/12/1955 | Was | Snyder | Promoted to active roster |   |   | Before |
| 7/13/1955 | Bal | Brown | Signed |   |   | Before |
| 7/14/1955 | Bal | Evers | Traded away | Cle |   | Before |
| 7/14/1955 | Bal | Wight | Acquired via trade | Cle |   | Before |
| 7/14/1955 | Cle | Altobelli | Demoted to reserve roster |   |   | Before |
| 7/14/1955 | Cle | Evers | Acquired via trade | Bal |   | Before |
| 7/14/1955 | Cle | Fain | Signed |   |   | Before |
| 7/14/1955 | Cle | Wight | Traded away | Bal |   | Before |
| 7/16/1955 | Bal | Coan | Traded away | ChA |   | Before |
| 7/16/1955 | Bal | Dyck | Promoted to active roster |   |   | Before |
| 7/16/1955 | Brk | Bessent | Promoted to active roster |   |   | Before |
| 7/16/1955 | Brk | Borkowski | Demoted to reserve roster |   |   | Before |
| 7/16/1955 | Brk | Craig | Promoted to active roster |   |   | Before |
| 7/16/1955 | Brk | Hughes | Demoted to reserve roster |   |   | Before |
| 7/16/1955 | ChA | Coan | Acquired via trade | Bal |   | Before |
| 7/16/1955 | KC | Fricano | Promoted to active roster |   |   | Before |
| 7/16/1955 | KC | Plarski | Promoted to active roster |   |   | Before |
| 7/16/1955 | KC | Sain | Released |   |   | Before |
| 7/18/1955 | ChN | Andre | Demoted to reserve roster |   |   | Before |
| 7/18/1955 | ChN | Tremel | Promoted to active roster |   |   | Before |
| 7/18/1955 | KC | Sleater | Demoted to reserve roster |   |   | After |
| 7/19/1955 | Det | Bunning | Promoted to active roster |   |   | Before |
| 7/19/1955 | Det | Maas | Demoted to reserve roster |   |   | Before |
| 7/19/1955 | NYA | Coleman | Activated from disabled list |   |   | Before |
| 7/20/1955 | NYA | Gray | Released |   |   | Before |
| 7/20/1955 | Pit | Hall | Promoted to active roster |   |   | Before |
| 7/21/1955 | Cin | Gross | Promoted to active roster |   |   | Before |
| 7/21/1955 | Cin | Jablonski | Demoted to reserve roster |   |   | Before |
| 7/21/1955 | Cin | Ridzik | Demoted to reserve roster |   |   | Before |
| 7/21/1955 | Cin | Smith | Signed |   |   | Before |
| 7/22/1955 | Cle | Kuhn | Placed on disabled list |   |   | Before |
| 7/22/1955 | Cle | Santiago | Promoted to active roster |   |   | Before |
| 7/22/1955 | NYN | Westrum | Placed on disabled list |   |   | Before |
| 7/25/1955 | ChA | Powell | Placed on disabled list |   |   | Before |
| 7/25/1955 | Phi | Kipper | Demoted to reserve roster |   |   | Before |
| 7/25/1955 | Phi | Micelotta | Promoted to active roster |   |   | Before |
| 7/26/1955 | Bal | Gray | Signed |   |   | Before |
| 7/26/1955 | ChA | Adams | Acquired via trade | Cin |   | Before |
| 7/26/1955 | Cin | Adams | Traded away | ChA |   | Before |
| 7/27/1955 | Bos | Baumann | Promoted to active roster |   |   | Before |
| 7/28/1955 | Brk | Meyer | Activated from disabled list |   |   | Before |
| 7/29/1955 | Bal | Majeski | Released |   |   | Before |
| 7/29/1955 | NYA | Grim | Placed on disabled list |   |   | Before |
| 7/29/1955 | NYA | Larsen | Promoted to active roster |   |   | Before |
| 7/30/1955 | Bal | Leppert | Promoted to active roster |   |   | Before |
| 7/30/1955 | Bal | Lopat | Acquired via trade | NYA |   | Before |
| 7/30/1955 | Bal | McDonald | Traded away | NYA |   | Before |
| 7/30/1955 | NYA | Lopat | Traded away | Bal |   | Before |
| 7/31/1955 | Cle | Maglie | Acquired via trade | NYN |   | Before |
| 7/31/1955 | Cle | Young | Demoted to reserve roster |   |   | Before |
| 7/31/1955 | NYN | Maglie | Traded away | Cle |   | Before |
| 8/1/1955 | Bal | Waitkus | Traded away | Phi |   | Before |
| 8/1/1955 | Bal | Waitkus | Activated from disabled list |   |   | Before |
| 8/1/1955 | Cin | Podbielan | Activated from disabled list |   |   | Before |
| 8/1/1955 | Mil | Adcock | Placed on disabled list |   |   | Before |
| 8/1/1955 | Mil | Taylor | Promoted to active roster |   |   | Before |
| 8/1/1955 | NYN | Williams | Placed on disabled list |   |   | Before |
| 8/1/1955 | Phi | Waitkus | Acquired via trade | Bal |   | Before |
| 8/2/1955 | ChA | Peterson | Signed |   |   | Before |
| 8/4/1955 | NYA | Hunter | Demoted to reserve roster |   |   | After |
| 8/4/1955 | NYA | Richardson | Promoted to active roster |   |   | After |
| 8/6/1955 | Cin | Brovia | Demoted to reserve roster |   |   | Before |
| 8/8/1955 | KC | Fricano | Demoted to reserve roster |   |   | Before |
| 8/10/1955 | KC | Plarski | Demoted to reserve roster |   |   | Before |
| 8/15/1955 | ChA | Fornieles | Demoted to reserve roster |   |   | Before |
| 8/15/1955 | NYA | Coleman | Promoted to active roster |   |   | Before |
| 8/15/1955 | NYA | Grim | Activated from disabled list |   |   | Before |
| 8/15/1955 | NYA | Konstanty | Demoted to reserve roster |   |   | Before |
| 8/15/1955 | NYA | Richardson | Demoted to reserve roster |   |   | Before |
| 8/15/1955 | NYN | Gardner | Promoted to active roster |   |   | Before |
| 8/16/1955 | Cin | Landrith | Activated from disabled list |   |   | Before |
| 8/16/1955 | Mil | Roselli | Promoted to active roster |   |   | Before |
| 8/16/1955 | Phi | Micelotta | Demoted to reserve roster |   |   | Before |
| 8/16/1955 | StL | Mackinson | Promoted to active roster |   |   | Before |
| 8/16/1955 | StL | Wooldridge | Demoted to reserve roster |   |   | Before |
| 8/18/1955 | Cle | Daley | Promoted to active roster |   |   | Before |
| 8/19/1955 | StL | McDaniel | Signed |   |   | Before |
| 8/20/1955 | Phi | Van Dusen | Signed |   |   | Before |
| 8/20/1955 | StL | Gettel | Promoted to active roster |   |   | Before |
| 8/20/1955 | StL | Lawrence | Demoted to reserve roster |   |   | Before |
| 8/26/1955 | ChA | Battey | Promoted to active roster |   |   | Before |
| 8/26/1955 | ChA | Coan | Traded away | NYN |   | Before |
| 8/26/1955 | ChA | Fornieles | Promoted to active roster |   |   | Before |
| 8/26/1955 | ChA | Northey | Promoted to active roster |   |   | Before |
| 8/26/1955 | Cle | Wertz | Placed on disabled list |   | 8/18/1955 | Before |
| 8/26/1955 | KC | Kume | Promoted to active roster |   |   | Before |
| 8/26/1955 | NYN | Coan | Acquired via trade | ChA |   | Before |
| 8/26/1955 | Pit | Peterson | Placed on disabled list |   |   | Before |
| 8/27/1955 | Pit | Swanson | Signed |   |   | Before |
| 8/31/1955 | KC | Schypinski | Promoted to active roster |   |   | Before |
| 9/1/1955 | Bal | Harrison | Promoted to active roster |   |   | Before |
| 9/1/1955 | Bal | Pyburn | Activated from disabled list |   |   | Before |
| 9/1/1955 | ChA | Papai | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChA | Powell | Activated from disabled list |   |   | Before |
| 9/1/1955 | ChN | Andre | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChN | Cohen | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChN | Lary | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChN | Morgan | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChN | Tappe,E | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChN | Thorpe | Promoted to active roster |   |   | Before |
| 9/1/1955 | ChN | Wade | Promoted to active roster |   |   | Before |
| 9/1/1955 | Cle | Kuhn | Activated from disabled list |   |   | Before |
| 9/1/1955 | KC | Bollweg | Promoted to active roster |   |   | Before |
| 9/1/1955 | KC | Burtschy | Promoted to active roster |   |   | Before |
| 9/1/1955 | KC | Craddock | Promoted to active roster |   |   | Before |
| 9/1/1955 | KC | Fricano | Promoted to active roster |   |   | Before |
| 9/1/1955 | KC | Plarski | Promoted to active roster |   |   | Before |
| 9/1/1955 | KC | Robertson | Promoted to active roster |   |   | Before |
| 9/1/1955 | KC | Trice | Promoted to active roster |   |   | Before |
| 9/1/1955 | Mil | Gorin | Promoted to active roster |   |   | Before |
| 9/1/1955 | Mil | Jay | Promoted to active roster |   |   | Before |
| 9/1/1955 | Mil | Pendleton | Promoted to active roster |   |   | Before |
| 9/1/1955 | Mil | Robinson | Promoted to active roster |   |   | Before |
| 9/1/1955 | NYA | Konstanty | Promoted to active roster |   |   | Before |
| 9/1/1955 | NYA | Martin | Activated from restricted list |   |   | Before |
| 9/1/1955 | NYA | Richardson | Promoted to active roster |   |   | Before |
| 9/1/1955 | NYN | Castleman | Promoted to active roster |   |   | Before |
| 9/1/1955 | Was | Korcheck | Promoted to active roster |   |   | Before |
| 9/2/1955 | Cle | Harrell | Promoted to active roster |   |   | Before |
| 9/2/1955 | Cle | Regalado | Promoted to active roster |   |   | Before |
| 9/2/1955 | Was | Clarke | Promoted to active roster |   |   | Before |
| 9/3/1955 | NYN | Dark | Placed on disabled list |   | 9/1/1955 | Before |
| 9/5/1955 | Pit | Powers | Promoted to active roster |   |   | Before |
| 9/6/1955 | Bal | Ferrarese | Promoted to active roster |   |   | Before |
| 9/6/1955 | Bal | Marquis | Promoted to active roster |   |   | Before |
| 9/6/1955 | Bal | Robinson | Promoted to active roster |   |   | Before |
| 9/6/1955 | Bos | Sullivan,H | Promoted to active roster |   |   | Before |
| 9/6/1955 | Brk | Moryn | Promoted to active roster |   |   | Before |
| 9/6/1955 | Brk | Templeton | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cin | Baczewski | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cin | Fisher | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cin | Hazle | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cin | Lane | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cin | Pearce | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cin | Valentine | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cle | Aguirre | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cle | Altobelli | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cle | Colavito | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cle | Pawloski | Promoted to active roster |   |   | Before |
| 9/6/1955 | Cle | Young | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | Black | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | King | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | Maas | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | Marlowe | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | Miller | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | Porter | Promoted to active roster |   |   | Before |
| 9/6/1955 | Det | Streuli | Promoted to active roster |   |   | Before |
| 9/6/1955 | KC | Gray | Promoted to active roster |   |   | Before |
| 9/6/1955 | KC | Keriazakos | Promoted to active roster |   |   | Before |
| 9/6/1955 | KC | Stewart | Promoted to active roster |   |   | Before |
| 9/6/1955 | Phi | Command | Promoted to active roster |   |   | Before |
| 9/6/1955 | Phi | Kazanski | Promoted to active roster |   |   | Before |
| 9/6/1955 | Phi | Lovenguth | Promoted to active roster |   |   | Before |
| 9/6/1955 | Phi | Owens | Promoted to active roster |   |   | Before |
| 9/6/1955 | Pit | Waters | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Alston | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Blasingame | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Jones | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Moford | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Rand | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Schofield | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Schultz | Promoted to active roster |   |   | Before |
| 9/6/1955 | StL | Wooldridge | Promoted to active roster |   |   | Before |
| 9/8/1955 | Det | Flowers | Traded away | StL |   | Before |
| 9/9/1955 | StL | Flowers | Acquired via trade | Det |   | Before |
| 9/9/1955 | StL | Tiefenauer | Traded away | Det |   | Before |
| 9/11/1955 | Bal | Dagres | Signed |   |   | Before |
| 9/11/1955 | Bos | Consolo | Promoted to active roster |   |   | Before |
| 9/11/1955 | Cin | Staley | Traded away | NYA |   | Before |
| 9/11/1955 | NYA | Blanchard | Promoted to active roster |   |   | Before |
| 9/11/1955 | NYA | Staley | Acquired via trade | Cin |   | Before |
| 9/11/1955 | Was | Becquer | Promoted to active roster |   |   | Before |
| 9/11/1955 | Was | Hyde | Promoted to active roster |   |   | Before |
| 9/11/1955 | Was | Lemon | Promoted to active roster |   |   | Before |
| 9/11/1955 | Was | Oldis | Promoted to active roster |   |   | Before |
| 9/11/1955 | Was | Roig | Promoted to active roster |   |   | Before |
| 9/11/1955 | Was | Stewart | Promoted to active roster |   |   | Before |
| 9/11/1955 | Was | Wright | Promoted to active roster |   |   | Before |
| 9/12/1955 | KC | Cox | Promoted to active roster |   |   | Before |
| 9/12/1955 | KC | Plarski | Demoted to reserve roster |   |   | Before |
| 9/12/1955 | Pit | Bell | Promoted to active roster |   |   | Before |
| 9/12/1955 | Pit | Grunwald | Promoted to active roster |   |   | Before |
| 9/12/1955 | Pit | King | Promoted to active roster |   |   | Before |
| 9/12/1955 | Pit | Montemayor | Promoted to active roster |   |   | Before |
| 9/12/1955 | Pit | Purkey | Promoted to active roster |   |   | Before |
| 9/12/1955 | Pit | Roberts | Promoted to active roster |   |   | Before |
| 9/12/1955 | Pit | Thies | Promoted to active roster |   |   | Before |
| 9/13/1955 | Cin | Bailey | Promoted to active roster |   |   | Before |
| 9/13/1955 | Cin | Jablonski | Promoted to active roster |   |   | Before |
| 9/14/1955 | KC | Saffell | Acquired via trade | Pit |   | Before |
| 9/14/1955 | NYA | Tettelbach | Promoted to active roster |   |   | Before |
| 9/14/1955 | NYA | Throneberry | Promoted to active roster |   |   | Before |
| 9/14/1955 | Pit | Saffell | Traded away | KC |   | Before |
| 9/14/1955 | StL | Lawrence | Promoted to active roster |   |   | Before |
| 9/15/1955 | Bal | Locke | Promoted to active roster |   |   | Before |
| 9/15/1955 | Bal | Segrist | Promoted to active roster |   |   | Before |
| 9/15/1955 | Bos | Gernert | Promoted to active roster |   |   | Before |
| 9/15/1955 | Bos | Kemmerer | Promoted to active roster |   |   | Before |
| 9/15/1955 | Bos | Malzone | Promoted to active roster |   |   | Before |
| 9/15/1955 | ChA | Esposito | Promoted to active roster |   |   | Before |
| 9/15/1955 | ChA | White | Promoted to active roster |   |   | Before |
| 9/15/1955 | KC | George | Promoted to active roster |   |   | Before |
| 9/17/1955 | Bal | Gray | Released |   |   | Before |
| 9/19/1955 | NYA | Berberet | Promoted to active roster |   |   | Before |
| 9/19/1955 | NYN | Burnside | Promoted to active roster |   |   | Before |
| 9/24/1955 | ChN | Fanning | Promoted to active roster |   |   | Before |
| 9/25/1955 | Brk | Howell | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | Brk | Hughes | Promoted to active roster |   |   | Before |
| 9/25/1955 | Brk | Koufax | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | Brk | Moryn | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | Brk | Walker | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | Brk | Walker | Promoted to active roster |   |   | Before |
| 9/25/1955 | NYA | Berberet | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Blanchard | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Konstanty | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Konstanty | Promoted to active roster |   |   | Before |
| 9/25/1955 | NYA | Leja | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Richardson | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Silvera | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Staley | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Tettelbach | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Throneberry | Demoted to reserve roster |   |   | Before |
| 9/25/1955 | NYA | Wiesler | Demoted to reserve roster |   |   | Before |