January 16, 2018
Mariners 
sign
Casey Lawrence
Mariners
sign
John Andreoli
March 07, 2018
Mariners
designate
Shawn Armstrong
for assignment
March 22, 2018
Ashton Goudeau
traded from
Royals
to
Mariners
March 25, 2018
Mariners
sign
Wade LeBlanc
as a free agent
March 28, 2018
Mariners
place
Erasmo Ramirez
on the injured list
Mariners
place
David Phelps
on the injured list
Mariners
place
Ben Gamel
on the injured list
March 30, 2018
Mariners
place
Mike Zunino
on the injured list
April 03, 2018
Mariners
place
Nelson Cruz
on the injured list
April 23, 2018
Roenis Elias
traded from
Red Sox
to
Mariners
May 01, 2018
Mariners
place
Dan Altavilla
on the injured list
Mariners
place
Erasmo Ramirez
on the injured list
May 14, 2018
Mariners
place
Robinson Cano
on the injured list
May 22, 2018
Mariners
place
Dee Strange-Gordon
on the injured list
May 25, 2018
Tommy Romero
traded from
Mariners
to
Rays
Alex Colome
traded from
Rays
to
Mariners
May 27, 2018
Mariners
place
Nick Vincent
on the injured list
Mariners
designate
Taylor Motter
for assignment
June 02, 2018
Mariners
sign
Ross Detwiler
June 08, 2018
Mariners
place
Dan Altavilla
on the injured list
June 12, 2018
Mariners
sign
Penn Murfee
Mariners
sign
Michael Plassmeyer
June 16, 2018
Mariners
sign
Logan Gilbert
July 05, 2018
Mariners
place
Mike Zunino
on the injured list
July 06, 2018
Mariners
sign
Cal Raleigh
July 13, 2018
Mariners
place
James Paxton
on the injured list
July 19, 2018
Mariners
sign
Justin Grimm
July 27, 2018
Seth Elledge
traded from
Mariners
to
Cardinals
July 30, 2018
Chase De Jong
traded from
Mariners
to
Twins
July 31, 2018
Mariners
place
Roenis Elias
on the injured list
Cameron Maybin
traded from
Marlins
to
Mariners
August 15, 2018
Mariners
place
James Paxton
on the injured list
August 17, 2018
Mariners
designate
John Andreoli
for assignment
Mariners
sign
Chris Mazza
August 22, 2018
Mariners
designate
Ross Detwiler
for assignment
August 27, 2018
Mariners
place
Marco Gonzales
on the injured list
September 28, 2018
Mariners
sign
Parker Markel
October 29, 2018
Cameron Maybin
became a free agent
David Phelps
became a free agent
Nelson Cruz
became a free agent
Andrew Romine
became a free agent
November 08, 2018
Guillermo Heredia
traded from
Mariners
to
Rays
Mike Zunino
traded from
Mariners
to
Rays
Michael Plassmeyer
traded from
Mariners
to
Rays
Jake Fraley
traded from
Rays
to
Mariners
November 09, 2018
Mariners
sign
Dylan Moore
as a free agent
November 15, 2018
Mariners
sign
R.J. Alaniz
as a free agent
November 19, 2018
Justus Sheffield
traded from
Yankees
to
Mariners
Erik Swanson
traded from
Yankees
to
Mariners
James Paxton
traded from
Mariners
to
Yankees
November 29, 2018
Mariners
release
Casey Lawrence
November 30, 2018
Alex Colome
traded from
Mariners
to
White Sox
Omar Narvaez
traded from
White Sox
to
Mariners
December 03, 2018
Justin Dunn
traded from
Mets
to
Mariners
Anthony Swarzak
traded from
Mets
to
Mariners
Robinson Cano
traded from
Mariners
to
Mets
Edwin Diaz
traded from
Mariners
to
Mets
Jay Bruce
traded from
Mets
to
Mariners
Jarred Kelenic
traded from
Mets
to
Mariners
Jean Segura
traded from
Mariners
to
Phillies
Carlos Santana
traded from
Phillies
to
Mariners
J.P. Crawford
traded from
Phillies
to
Mariners
December 13, 2018
Carlos Santana
traded from
Mariners
to
Indians
December 20, 2018
Mariners
sign
Zac Rosscup
as a free agent