Mariners Roster & Staff
Transactions
| Date | Transaction |
| 05/18/26 | Seattle Mariners activated 1B Patrick Wisdom from the 10-day injured list. |
| 05/18/26 | Seattle Mariners recalled LHP Robinson Ortiz from Tacoma Rainiers. |
| 05/18/26 | Seattle Mariners optioned RHP Domingo Gonzalez to Tacoma Rainiers. |
| 05/18/26 | Seattle Mariners optioned 3B Leo Rivas to Tacoma Rainiers. |
| 05/18/26 | Seattle Mariners selected the contract of CF Brennen Davis from Tacoma Rainiers. |
| 05/18/26 | Seattle Mariners optioned CF Brennen Davis to Tacoma Rainiers. |
| 05/17/26 | Seattle Mariners placed 3B Brendan Donovan on the 10-day injured list retroactive to May 16, 2026. Left groin muscle strain. |
| 05/17/26 | Seattle Mariners recalled SS Colt Emerson from Tacoma Rainiers. |
| 05/14/26 | Seattle Mariners activated LHP José A. Ferrer from the paternity list. |
| 05/14/26 | Seattle Mariners sent RHP Matt Brash on a rehab assignment to Tacoma Rainiers. |
| 05/14/26 | Seattle Mariners placed C Cal Raleigh on the 10-day injured list. Right oblique strain. |
| 05/14/26 | Seattle Mariners traded LHP José Suarez to Athletics for cash. |
| 05/14/26 | Seattle Mariners recalled C Jhonny Pereda from Tacoma Rainiers. |
| 05/14/26 | Seattle Mariners optioned LHP Josh Simpson to Tacoma Rainiers. |
| 05/13/26 | Seattle Mariners activated RHP Bryce Miller from the 15-day injured list. |
| 05/13/26 | Seattle Mariners designated LHP José Suarez for assignment. |
| 05/11/26 | Seattle Mariners placed LHP José A. Ferrer on the paternity list. |
| 05/11/26 | Seattle Mariners recalled RHP Domingo Gonzalez from Tacoma Rainiers. |
| 05/09/26 | Houston Astros claimed LF Rhylan Thomas off waivers from Seattle Mariners. |
| 05/08/26 | Seattle Mariners signed free agent RHP Scott Rouse to a minor league contract. |
| 05/08/26 | Seattle Mariners activated 3B Brendan Donovan from the 10-day injured list. |
| 05/08/26 | Seattle Mariners optioned C Jhonny Pereda to Tacoma Rainiers. |
| 05/07/26 | Seattle Mariners signed LHP Dominic Castellano. |
| 05/07/26 | Seattle Mariners signed free agent RHP Sam Whiting to a minor league contract. |
| 05/06/26 | Seattle Mariners signed free agent LHP Cole Cheatham to a minor league contract. |
| 05/06/26 | Seattle Mariners sent RHP Bryce Miller on a rehab assignment to Everett AquaSox. |
| 05/05/26 | Seattle Mariners sent 3B Brendan Donovan on a rehab assignment to Arkansas Travelers. |
| 05/05/26 | Seattle Mariners sent 1B Patrick Wisdom on a rehab assignment to Tacoma Rainiers. |
| 05/05/26 | Seattle Mariners sent 3B Brendan Donovan on a rehab assignment to Arkansas Travelers. |
| 05/04/26 | Seattle Mariners activated LHP José Suarez. |
| 05/04/26 | Seattle Mariners placed LHP Gabe Speier on the 15-day injured list retroactive to May 3, 2026. Left shoulder inflammation. |
| 05/04/26 | Seattle Mariners recalled LHP Josh Simpson from Tacoma Rainiers. |
| 05/04/26 | Seattle Mariners optioned RHP Cole Wilcox to Tacoma Rainiers. |
| 05/03/26 | Seattle Mariners designated LF Rhylan Thomas for assignment. |
| 05/03/26 | Seattle Mariners sent RF Victor Robles on a rehab assignment to Tacoma Rainiers. |
| 05/03/26 | Seattle Mariners claimed LHP José Suarez off waivers from Atlanta Braves. |
| 05/02/26 | Seattle Mariners placed 3B Will Wilson on the 10-day injured list retroactive to April 30, 2026. Left thumb fracture. |
| 05/02/26 | Seattle Mariners recalled C Jhonny Pereda from Tacoma Rainiers. |
| 05/02/26 | Seattle Mariners optioned LHP Josh Simpson to Tacoma Rainiers. |
| 05/02/26 | Seattle Mariners selected the contract of RHP Nick Davila from Arkansas Travelers. |
| 05/01/26 | Seattle Mariners placed RHP Matt Brash on the 15-day injured list retroactive to April 30, 2026. Right lat inflammation. |
| 05/01/26 | Seattle Mariners purchased contract of RHP Adam Smith. |
| 05/01/26 | Seattle Mariners recalled LHP Josh Simpson from Tacoma Rainiers. |