Cardinals Roster & Staff
Transactions
| Date | Transaction |
| 05/30/21 | St. Louis Cardinals placed RHP Kodi Whitley on the 10-day injured list. Mid back spasms. |
| 05/30/21 | St. Louis Cardinals signed free agent LHP Tyler Pike to a minor league contract. |
| 05/30/21 | St. Louis Cardinals recalled RHP Seth Elledge from Memphis Redbirds. |
| 05/29/21 | St. Louis Cardinals optioned RHP Johan Oviedo to Memphis Redbirds. |
| 05/29/21 | St. Louis Cardinals placed RHP Miles Mikolas on the 60-day injured list. Right forearm tightness. |
| 05/29/21 | St. Louis Cardinals selected the contract of 3B Jose Rondon from Memphis Redbirds. |
| 05/29/21 | St. Louis Cardinals placed 2B Max Moroff on the 10-day injured list. Left shoulder subluxation. |
| 05/29/21 | St. Louis Cardinals recalled RHP Junior Fernandez from Memphis Redbirds. |
| 05/28/21 | St. Louis Cardinals recalled RHP Johan Oviedo from Memphis Redbirds. |
| 05/28/21 | St. Louis Cardinals optioned RHP Junior Fernandez to Memphis Redbirds. |
| 05/27/21 | St. Louis Cardinals activated LF Tyler O'Neill from the 10-day injured list. |
| 05/27/21 | St. Louis Cardinals activated LF Tyler O'Neill from the 10-day injured list. |
| 05/27/21 | St. Louis Cardinals optioned 1B John Nogowski to Memphis Redbirds. |
| 05/25/21 | St. Louis Cardinals recalled 1B John Nogowski from Memphis Redbirds. |
| 05/25/21 | St. Louis Cardinals placed CF Harrison Bader on the 10-day injured list. Right rib hairline fracture. |
| 05/25/21 | St. Louis Cardinals sent LHP Andrew Miller on a rehab assignment to Memphis Redbirds. |
| 05/23/21 | St. Louis Cardinals recalled RHP Junior Fernandez from Memphis Redbirds. |
| 05/23/21 | St. Louis Cardinals placed RHP Miles Mikolas on the 10-day injured list. Right forearm tightness. |
| 05/22/21 | St. Louis Cardinals optioned RHP Seth Elledge to Memphis Redbirds. |
| 05/22/21 | St. Louis Cardinals activated RHP Miles Mikolas. |
| 05/21/21 | St. Louis Cardinals activated RHP Carlos Martinez from the 10-day injured list. |
| 05/20/21 | St. Louis Cardinals optioned 1B John Nogowski to Memphis Redbirds. |
| 05/18/21 | St. Louis Cardinals activated RHP Daniel Ponce de Leon. |
| 05/18/21 | St. Louis Cardinals placed LF Tyler O'Neill on the 10-day injured list. Left middle finger fracture. |
| 05/18/21 | St. Louis Cardinals activated 1B John Nogowski. |
| 05/18/21 | St. Louis Cardinals optioned RHP Junior Fernandez to Memphis Redbirds. |
| 05/15/21 | St. Louis Cardinals recalled RHP Junior Fernandez from Memphis Redbirds. |
| 05/15/21 | St. Louis Cardinals optioned RHP Johan Oviedo to Memphis Redbirds. |
| 05/14/21 | St. Louis Cardinals selected the contract of 2B Max Moroff. |
| 05/14/21 | St. Louis Cardinals selected the contract of 2B Max Moroff from Memphis Redbirds. |
| 05/14/21 | St. Louis Cardinals selected the contract of 2B Max Moroff. |
| 05/14/21 | St. Louis Cardinals placed SS Paul DeJong on the 10-day injured list. Left rib non-displaced fracture,. |
| 05/14/21 | St. Louis Cardinals placed RHP Jordan Hicks on the 60-day injured list. Right elbow inflammation. |
| 05/13/21 | St. Louis Cardinals sent RHP Daniel Ponce de Leon on a rehab assignment to Memphis Redbirds. |
| 05/12/21 | St. Louis Cardinals signed free agent RF Clint Coulter to a minor league contract. |
| 05/11/21 | St. Louis Cardinals recalled RHP Johan Oviedo from Memphis Redbirds. |
| 05/11/21 | St. Louis Cardinals placed RHP Carlos Martinez on the 10-day injured list. Right ankle injury. |
| 05/08/21 | St. Louis Cardinals activated C Yadier Molina from the 10-day injured list. |
| 05/08/21 | St. Louis Cardinals optioned C Ali Sanchez to Memphis Redbirds. |
| 05/07/21 | St. Louis Cardinals sent 1B John Nogowski on a rehab assignment to Memphis Redbirds. |
| 05/06/21 | St. Louis Cardinals optioned LHP Bernardo Flores Jr. to Memphis Redbirds. |
| 05/06/21 | St. Louis Cardinals optioned RHP Johan Oviedo to Memphis Redbirds. |
| 05/06/21 | St. Louis Cardinals recalled CF Lane Thomas from Memphis Redbirds. |
| 05/05/21 | St. Louis Cardinals sent RHP Miles Mikolas on a rehab assignment to Memphis Redbirds. |
| 05/05/21 | St. Louis Cardinals recalled LHP Bernardo Flores Jr. from Memphis Redbirds. |
| 05/04/21 | St. Louis Cardinals recalled RHP Johan Oviedo from Memphis Redbirds. |
| 05/04/21 | St. Louis Cardinals placed RHP Jordan Hicks on the 10-day injured list. Right elbow inflammation. |
| 05/03/21 | St. Louis Cardinals activated RHP Adam Wainwright from the 10-day injured list. |
| 05/03/21 | St. Louis Cardinals optioned LF Austin Dean to Memphis Redbirds. |