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| 2021-06-04 23:19:54 | St. Louis 5th Alarm | Jared Jones | Add/Drop | | |
| 2021-06-04 22:37:24 | Santiago Sharks | | Promoted | Antonio Johnson | San Diego Sabercats |
| 2021-06-04 19:30:00 | Orlando Bombers | Theo Stanton | Acquired via waivers | Jeffrey McBride | Waiver |
| 2021-06-04 19:30:00 | Phoenix Kangaroos | Mark Batterson | Acquired via waivers | Fran Vickers | Waiver |
| 2021-06-04 19:24:00 | Boston Bannerman | Hans Sterling | Acquired via trade | 1st round pick in season 31 | St. Louis 5th Alarm |
| 2021-06-04 19:24:00 | Boston Bannerman | 2nd round pick in season 31 | Acquired via trade | | St. Louis 5th Alarm |
| 2021-06-04 19:22:00 | Cincinnati Skyliners | Zachary Sledge | Acquired via trade | 2nd round pick in season 31 | St. Louis 5th Alarm |
| 2021-06-04 19:22:00 | Cincinnati Skyliners | 3rd round pick in season 31 | Acquired via trade | | St. Louis 5th Alarm |
| 2021-06-04 19:20:00 | St. Louis 5th Alarm | Don Kunz | Acquired via trade | 1st round pick in season 31 | San Diego Sabercats |
| 2021-06-04 17:51:48 | Boston Bannerman | | Drop | Howard Mallory | |
| 2021-06-04 16:38:02 | South Dakota Blackhawks | | Promoted | Jeffrey Knight | Philadelphia Assassins |
| 2021-06-04 16:37:36 | Philadelphia Assassins | | Demoted | Chad Hammond | South Dakota Blackhawks |
| 2021-06-04 16:21:50 | Indianapolis Tornadoes | | Demoted | Dante Joseph | Buenos Aires Eagles |
| 2021-06-04 16:21:26 | Buenos Aires Eagles | | Promoted | Sylvester Dixon | Indianapolis Tornadoes |
| 2021-06-03 14:50:58 | San Francisco Golden Gators | | Demoted | Garrett Nelson | Little Rock Fighting Farmers |
| 2021-06-03 14:50:36 | Little Rock Fighting Farmers | | Promoted | Eric Spilde | San Francisco Golden Gators |
| 2021-06-03 11:36:42 | Phoenix Kangaroos | Israel Varble | Add/Drop | Philip Nelson | |
| 2021-06-03 11:26:46 | Phoenix Kangaroos | Curtis Jackson | Add/Drop | Horace Rosen | |
| 2021-06-03 07:38:48 | San Diego Sabercats | | Demoted | Sonny Kincaid | Santiago Sharks |
| 2021-06-03 04:35:54 | Orlando Bombers | Clyde Sedale | Add/Drop | John Stockman | |
| 2021-06-03 04:33:00 | Orlando Bombers | Micha Czapla | Add/Drop | Edmund Gutierez | |
| 2021-06-02 17:56:56 | Minneapolis Bricklayers | Hugh Seidl | Add/Drop | Roberto Morse | |
| 2021-06-02 10:36:32 | South Dakota Blackhawks | | Promoted | Chad Hammond | Philadelphia Assassins |
| 2021-06-02 10:25:28 | Philadelphia Assassins | | Demoted | Jeffrey Knight | South Dakota Blackhawks |
| 2021-06-02 10:25:00 | South Dakota Blackhawks | | Promoted | Juan Garcia | Philadelphia Assassins |