| | SS | Placed on 10-Day IL (Sprained left thumb) |
| | SS | Purchased From Minors (Signed) |
| | P | Designated for Assignment (Signed) |
| | P | Outrighted to Minors (Signed) |
| | SS | Placed on 10-Day IL (Strained right hamstring) |
| | P | Placed on 10-Day IL (Left shoulder strain) |
| | P | Designated for Assignment (Signed) |
| | P | Signed as Free Agent (one-year contract) |
| | 3B | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Purchased From Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | 1B | Purchased From Minors (Signed) |
| | SS | Purchased From Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | 2B | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | 3B | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | CF | Placed on Restricted List (opting out of 2021 season) |
| | 1B | Signed to a Minor League Contract (Signed) |
| | 1B | Signed to a Minor League Contract (Signed) |
| | 3B | Traded (for 3B Nolan Arenado, six-player trade) From |
| | P | Traded (for 3B Nolan Arenado, six-player trade) From |
| | 3B | Traded (for LHP Austin Gomber, six-player trade) To |
| | 2B | Retired (Signed) |
| | SS | Signed to a Minor League Contract (Signed) |
| | LF | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | 2B | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | RP | Signed to Play in Korea (DC Dinos) |
| | P | Signed (avoids arbitration) |
| | P | Signed to a Minor League Contract (Signed) |
| | P | Drafted Via Rule 5 (Signed) |
| | P | Traded (for INF Christian Koss) From |
| | LF | Free Agent - No Contract Offer (non-tendered) |
| | C | Free Agent - No Contract Offer (non-tendered) |
| | P | Free Agent - No Contract Offer (non-tendered) |
| | C | Signed (avoids arbitration) |
| | P | Signed (avoids arbitration) |
| | P | Acquired Off Waivers (Signed) To |
| | P | Outrighted to Minors (Signed) |
| | CF | Traded (for RHP Jeff Hoffman, four-player deal) From |
| | P | Traded (for RHP Robert Stephenson, 4-player deal) To |
| | P | Traded (for RHP Jeff Hoffman, four-player deal) From |
| | LF | Signed to a Minor League Contract (Signed) |
| | P | Designated for Assignment (Signed) |
| | P | Purchased From Minors (Signed) |
| | P | Designated for Assignment (Signed) |
| | 3B | Purchased From Minors (Signed) |
| | P | Purchased From Minors (Signed) |
| | 2B | Purchased From Minors (Signed) |
| | 3B | Signed to a Minor League Contract (Signed) |
| | C | Signed to a Minor League Contract (Signed) |
| | SP | Signed to a Minor League Contract (Signed) |
| | DH | Signed to a Minor League Contract (Signed) |
| | P | Signed to a Minor League Contract (Signed) |
| | P | Declared Free Agency (Signed) |
| | CF | Reinstated From Restricted List (Signed) |
| | P | Outrighted to Minors (Signed) |
| | P | Declared Free Agency (Signed) |
| | CF | Declared Free Agency (Signed) |
| | P | Reinstated From Restricted List (Signed) |
| | SS | Declared Free Agency (Signed) |
| | 2B | Declared Free Agency (Signed) |
| | CF | Declared Free Agency (Signed) |
| | C | Declared Free Agency (Signed) |
| | P | Refused Minor League Assignment - Free Agent (Signed) |
| | P | Outrighted to Minors (Signed) |
| | SS | Removed From 10-Day IL (Strained left hamstring) |
| | P | Designated for Assignment (Signed) |
| | P | Removed From 10-Day IL (Right shoulder inflammation) |
| | P | Reinstated from Illegal Substance Suspension (Signed) |
| | 3B | Removed From 10-Day IL (Left shoulder bone bruise) |
| | CF | Called Up from Minors (Signed) |
| | C | Called Up from Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | SS | Removed From 10-Day IL (Right shoulder capsular strain) |
| | P | Called Up from Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Called Up from Minors (recalled as 29th roster player) |
| | P | Sent to Minors (Signed) |
| | P | Return of 27th man (return of 29th roster player) |
| | P | Cleared Waivers and Became a Free Agent (Signed) |
| | P | Purchased From Minors (Signed) |
| | P | Released (Signed) |
| | 3B | Placed on 10-Day IL (Left shoulder bone bruise) |
| | RF | Called Up from Minors (Signed) |
| | P | Designated for Assignment (Signed) |
| | P | Called Up from Minors (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Purchased From Minors (Signed) |
| | RF | Sent to Minors (Signed) |
| | P | Called Up from Minors (Signed) |
| | SP | Retired (Signed) |
| | P | Sent to Minors (Signed) |
| | P | Removed From 10-Day IL (Strained right shoulder) |
