January 30, 2021

Cole Irvin traded from Phillies  to Athletics 

February 02, 2021

Athletics  sign Deolis Guerra

February 06, 2021

February 10, 2021

Athletics  sign Jed Lowrie as a free agent

February 12, 2021

February 16, 2021

Athletics  sign Mike Fiers as a free agent

February 18, 2021

Athletics  place Frankie Montas on the injured list

Athletics  sign Sergio Romo as a free agent

February 19, 2021

Athletics  sign Yusmeiro Petit as a free agent

February 22, 2021

Athletics  designate Dustin Fowler for assignment

February 23, 2021

Athletics  designate Paul Blackburn for assignment

Athletics  sign Mitch Moreland as a free agent

February 24, 2021

Dustin Fowler traded from Athletics  to Pirates 

March 26, 2021

Athletics  release Deolis Guerra

Athletics  sign Deolis Guerra as a free agent

March 27, 2021

Athletics  sign Deolis Guerra as a free agent

April 01, 2021

Athletics  place Mike Fiers on the injured list

Athletics  designate Skye Bolt for assignment

April 05, 2021

Athletics  place Chad Pinder on the injured list

April 06, 2021

Athletics  place Burch Smith on the injured list

Athletics  place Reymin Guduan on the injured list

April 08, 2021

Athletics  place A.J. Puk on the injured list

April 19, 2021

Athletics  designate Ka'ai Tom for assignment

May 01, 2021

Athletics  sign Cam Bedrosian

May 02, 2021

Athletics  place Jesus Luzardo on the injured list

Athletics  place J.B. Wendelken on the injured list

May 04, 2021

Athletics  place Aramis Garcia on the injured list

May 05, 2021

Skye Bolt traded from Giants  to Athletics 

May 08, 2021

Athletics  place Mike Fiers on the injured list

May 18, 2021

Athletics  place Mitch Moreland on the injured list

May 21, 2021

Athletics  place Mike Fiers on the injured list

May 28, 2021

Athletics  place Reymin Guduan on the injured list

June 01, 2021

Athletics  place Ramon Laureano on the injured list

June 08, 2021

Athletics  designate Reymin Guduan for assignment

June 19, 2021

Athletics  place Stephen Piscotty on the injured list

June 25, 2021

Athletics  place Mark Canha on the injured list

June 29, 2021

Athletics  designate Cam Bedrosian for assignment

July 02, 2021

Sam Moll traded from Diamondbacks  to Athletics 

July 03, 2021

Athletics  designate Jordan Weems for assignment

July 04, 2021

Athletics  place Mitch Moreland on the injured list

July 08, 2021

Athletics  place Chad Pinder on the injured list

July 16, 2021

Athletics  designate Frank Schwindel for assignment

July 26, 2021

July 28, 2021

July 30, 2021

Athletics  designate Domingo Acevedo for assignment

Athletics  designate Jacob Wilson for assignment

July 31, 2021

Athletics  place James Kaprielian on the injured list

Athletics  release Domingo Acevedo

August 02, 2021

Athletics  sign Domingo Acevedo

August 04, 2021

Athletics  sign Khris Davis

August 10, 2021

Athletics  designate J.B. Wendelken for assignment

August 18, 2021

Athletics  place Chris Bassitt on the injured list

August 21, 2021

Athletics  place Stephen Piscotty on the injured list

August 27, 2021

Athletics  place Seth Brown on the injured list

August 31, 2021

Athletics  place Mitch Moreland on the injured list

September 14, 2021

Athletics  designate Burch Smith for assignment

September 18, 2021

Athletics  place Daulton Jefferies on the injured list

September 20, 2021

Athletics  designate Aramis Garcia for assignment

September 22, 2021

Athletics  release Aramis Garcia

September 26, 2021

Athletics  place Jed Lowrie on the injured list

Athletics  place Elvis Andrus on the injured list

September 27, 2021

Athletics  designate Michael Feliz for assignment

October 01, 2021

Athletics  place Vimael Machin on the injured list

Athletics  release Michael Feliz

October 16, 2021

Athletics  sign Dany Jimenez

November 03, 2021

Khris Davis became a free agent

Sergio Romo became a free agent

Yusmeiro Petit became a free agent

Mark Canha became a free agent

Mitch Moreland became a free agent

Mike Fiers became a free agent

Yan Gomes became a free agent

Jed Lowrie became a free agent

Josh Harrison became a free agent

Starling Marte became a free agent

November 04, 2021

Jake Diekman became a free agent

Andrew Chafin became a free agent

November 19, 2021

Brent Honeywell Jr. traded from Rays  to Athletics 

November 25, 2021

Athletics  sign Christian Bethancourt

December 03, 2021

Athletics  sign Drew Jackson