January 29, 2020

Mariners  sign Dietrich Enns

February 03, 2020

Mariners  designate Matt Festa for assignment

February 11, 2020

Mariners  sign Manny Banuelos

February 12, 2020

Mariners  sign Taijuan Walker as a free agent

February 21, 2020

Mariners  designate Phillips Valdez for assignment

June 28, 2020

Mariners  place Mitch Haniger on the injured list

July 22, 2020

Mariners  place Tom Murphy on the injured list

July 23, 2020

Mariners  sign Bryan Shaw as a free agent

July 27, 2020

Mariners  place Brandon Brennan on the injured list

August 04, 2020

Mariners  place Kendall Graveman on the injured list

August 10, 2020

Mariners  place Carl Edwards on the injured list

Mariners  designate Patrick Wisdom for assignment

Mariners  sign Seth Frankoff

August 11, 2020

Mariners  place Brady Lail on the injured list

August 14, 2020

Mariners  release Patrick Wisdom

August 15, 2020

Mariners  place Nestor Cortes on the injured list

Mariners  designate Bryan Shaw for assignment

August 19, 2020

Mariners  designate Dan Vogelbach for assignment

Jimmy Yacabonis traded from Padres  to Mariners 

August 20, 2020

Mariners  place Erik Swanson on the injured list

August 22, 2020

Mariners  place Dylan Moore on the injured list

August 24, 2020

Dan Vogelbach traded from Mariners  to Blue Jays 

August 27, 2020

Taijuan Walker traded from Mariners  to Blue Jays 

August 31, 2020

Taylor Williams traded from Mariners  to Padres 

September 07, 2020

Mariners  place Sam Haggerty on the injured list

September 11, 2020

Mariners  place Shed Long on the injured list

September 15, 2020

Mariners  designate Jimmy Yacabonis for assignment

September 17, 2020

Matt Brash traded from Padres  to Mariners 

September 22, 2020

Mariners  place Dylan Moore on the injured list

September 23, 2020

Mariners  place Jake Fraley on the injured list

September 27, 2020

Mariners  place Luis Torrens on the injured list

October 28, 2020

Dee Strange-Gordon became a free agent

Kendall Graveman became a free agent

October 29, 2020

Mariners  sign Kendall Graveman as a free agent

November 06, 2020

Mariners  sign Vinny Nittoli

November 16, 2020

Mariners  sign Brady Lail

November 20, 2020

Mariners  sign Drew Steckenrider

Mariners  sign Jose Godoy

December 15, 2020

Rafael Montero traded from Rangers  to Mariners 

December 16, 2020

Mariners  sign Keynan Middleton as a free agent

December 18, 2020

Mariners  designate Tim Lopes for assignment

Mariners  sign Chris Flexen as a free agent

December 29, 2020

Mariners  sign Jimmy Yacabonis