Athletics Roster & Staff
Transactions
| Date | Transaction |
| 07/31/21 | Oakland Athletics released RHP Domingo Acevedo. |
| 07/31/21 | Oakland Athletics optioned C Aramis Garcia to Las Vegas Aviators. |
| 07/31/21 | Oakland Athletics activated 2B Josh Harrison. |
| 07/31/21 | Oakland Athletics placed RHP James Kaprielian on the 10-day injured list. Right shoulder impingement. |
| 07/30/21 | Washington Nationals traded C Yan Gomes, 2B Josh Harrison and cash to Oakland Athletics for RHP Richard Guasch, RHP Seth Shuman and C Drew Millas. |
| 07/30/21 | Oakland Athletics designated RHP Domingo Acevedo for assignment. |
| 07/30/21 | Washington Nationals traded C Yan Gomes, 2B Josh Harrison and cash to Oakland Athletics for RHP Richard Guasch, RHP Seth Shuman and C Drew Millas. |
| 07/30/21 | Oakland Athletics designated 2B Jacob Wilson for assignment. |
| 07/30/21 | Washington Nationals traded C Yan Gomes, 2B Josh Harrison and cash to Oakland Athletics for RHP Richard Guasch, RHP Seth Shuman and C Drew Millas. |
| 07/30/21 | Washington Nationals traded C Yan Gomes, 2B Josh Harrison and cash to Oakland Athletics for RHP Richard Guasch, RHP Seth Shuman and C Drew Millas. |
| 07/30/21 | Washington Nationals traded C Yan Gomes, 2B Josh Harrison and cash to Oakland Athletics for RHP Richard Guasch, RHP Seth Shuman and C Drew Millas. |
| 07/29/21 | Oakland Athletics activated LF Starling Marte. |
| 07/29/21 | Oakland Athletics optioned 2B Jacob Wilson to Las Vegas Aviators. |
| 07/28/21 | Miami Marlins traded LF Starling Marte to Oakland Athletics for LHP Jesus Luzardo. |
| 07/28/21 | Miami Marlins traded LF Starling Marte to Oakland Athletics for LHP Jesus Luzardo. |
| 07/27/21 | Oakland Athletics optioned LHP Sam Moll to Las Vegas Aviators. |
| 07/27/21 | Oakland Athletics activated LHP Andrew Chafin. |
| 07/26/21 | Oakland Athletics signed 3B Zack Gelof. |
| 07/26/21 | Oakland Athletics signed C CJ Rodriguez. |
| 07/26/21 | Chicago Cubs traded LHP Andrew Chafin to Oakland Athletics for 1B Greg Deichmann and RHP Daniel Palencia. |
| 07/26/21 | Oakland Athletics signed OF Denzel Clarke. |
| 07/26/21 | Chicago Cubs traded LHP Andrew Chafin to Oakland Athletics for 1B Greg Deichmann and RHP Daniel Palencia. |
| 07/26/21 | Chicago Cubs traded LHP Andrew Chafin to Oakland Athletics for 1B Greg Deichmann and RHP Daniel Palencia. |
| 07/21/21 | Oakland Athletics signed 2B Mariano Ricciardi. |
| 07/21/21 | Oakland Athletics signed free agent 1B Nick Brueser to a minor league contract. |
| 07/21/21 | Oakland Athletics signed RHP Mason Miller. |
| 07/21/21 | Oakland Athletics signed LHP Colton Johnson. |
| 07/21/21 | Oakland Athletics signed RHP Blake Beers. |
| 07/21/21 | Oakland Athletics signed RHP Luke Anderson. |
| 07/21/21 | Oakland Athletics signed SS Jack WInkler. |
| 07/21/21 | Oakland Athletics signed LHP Eduardo Rivera. |
| 07/21/21 | Oakland Athletics signed free agent LHP Jack Owen to a minor league contract. |
| 07/21/21 | Oakland Athletics signed C Shane McGuire. |
| 07/21/21 | Oakland Athletics signed RHP Mitch Myers. |
| 07/21/21 | Oakland Athletics signed RHP Kyle Virbitsky. |
| 07/21/21 | Oakland Athletics signed SS Max Muncy. |
| 07/21/21 | Oakland Athletics signed RHP Grant Holman. |
| 07/21/21 | Oakland Athletics signed 3B Brett Harris. |
| 07/21/21 | Oakland Athletics signed SS Drew Swift. |
| 07/21/21 | Oakland Athletics signed RHP Aaron Holiday. |
| 07/21/21 | Oakland Athletics signed OF Jonny Butler. |
| 07/21/21 | Oakland Athletics signed RHP Hunter Breault. |
| 07/18/21 | Chicago Cubs claimed 1B Frank Schwindel off waivers from Oakland Athletics. |
| 07/17/21 | Oakland Athletics optioned CF Skye Bolt to Las Vegas Aviators. |
| 07/17/21 | Oakland Athletics activated LF Mark Canha from the 10-day injured list. |
| 07/16/21 | Oakland Athletics designated 1B Frank Schwindel for assignment. |
| 07/16/21 | Oakland Athletics activated 1B Mitch Moreland from the 10-day injured list. |
| 07/12/21 | Oakland Athletics optioned 1B Frank Schwindel to Las Vegas Aviators. |
| 07/08/21 | Oakland Athletics placed LF Chad Pinder on the 10-day injured list. Right hamstring strain. |
| 07/08/21 | Oakland Athletics selected the contract of 2B Jacob Wilson from Las Vegas Aviators. |
| 07/05/21 | Arizona Diamondbacks claimed RHP Jordan Weems off waivers from Oakland Athletics. |
| 07/04/21 | Oakland Athletics placed 1B Mitch Moreland on the 10-day injured list. |
| 07/04/21 | Oakland Athletics activated RF Stephen Piscotty. |
| 07/03/21 | Oakland Athletics designated RHP Jordan Weems for assignment. |
| 07/03/21 | Oakland Athletics sent RF Stephen Piscotty on a rehab assignment to Stockton Ports. |
| 07/03/21 | Oakland Athletics selected the contract of LHP Sam Moll from Las Vegas Aviators. |
| 07/03/21 | Oakland Athletics optioned RHP Domingo Acevedo to Las Vegas Aviators. |
| 07/02/21 | Oakland Athletics sent RHP Cam Bedrosian outright to Las Vegas Aviators. |
| 07/02/21 | Arizona Diamondbacks traded LHP Sam Moll to Oakland Athletics for cash. |