Mariners Roster & Staff
Transactions
| Date | Transaction |
| 06/30/26 | Seattle Mariners recalled RHP Cole Wilcox from Tacoma Rainiers. |
| 06/30/26 | Seattle Mariners optioned LHP Josh Simpson to Tacoma Rainiers. |
| 06/29/26 | Seattle Mariners placed DH Rob Refsnyder on the 10-day injured list retroactive to June 27, 2026. Right knee inflammation. |
| 06/29/26 | San Francisco Giants traded 1B Buddy Kennedy to Seattle Mariners for cash. |
| 06/27/26 | Seattle Mariners optioned RHP Alex Hoppe to Tacoma Rainiers. |
| 06/27/26 | Seattle Mariners recalled LHP Josh Simpson from Tacoma Rainiers. |
| 06/25/26 | Seattle Mariners sent 3B Miles Mastrobuoni outright to Tacoma Rainiers. |
| 06/23/26 | Seattle Mariners activated LF Randy Arozarena from the 10-day injured list. |
| 06/23/26 | Seattle Mariners optioned RF Connor Joe to Tacoma Rainiers. |
| 06/20/26 | Seattle Mariners sent CF Curtis Washington Jr. outright to Everett AquaSox. |
| 06/19/26 | Seattle Mariners designated 3B Miles Mastrobuoni for assignment. |
| 06/19/26 | Seattle Mariners selected the contract of 3B Weston Wilson from Tacoma Rainiers. |
| 06/18/26 | Seattle Mariners signed free agent RHP Adalberto Vallenilla to a minor league contract. |
| 06/18/26 | Seattle Mariners signed free agent RHP Ferny Barreda to a minor league contract. |
| 06/17/26 | Seattle Mariners optioned CF Curtis Washington Jr. to Everett AquaSox. |
| 06/17/26 | Seattle Mariners recalled RF Connor Joe from Tacoma Rainiers. |
| 06/17/26 | Seattle Mariners traded RHP Randy Dobnak to Kansas City Royals for cash. |
| 06/16/26 | Seattle Mariners transferred 3B Will Wilson from the 10-day injured list to the 60-day injured list. Left thumb fracture. |
| 06/16/26 | Seattle Mariners activated SS J.P. Crawford from the 10-day injured list. |
| 06/16/26 | Seattle Mariners activated C Cal Raleigh from the 10-day injured list. |
| 06/16/26 | Seattle Mariners placed LF Randy Arozarena on the 10-day injured list retroactive to June 13, 2026. Left hamstring strain. |
| 06/16/26 | Seattle Mariners optioned C Jhonny Pereda to Tacoma Rainiers. |
| 06/16/26 | Seattle Mariners selected the contract of CF Curtis Washington Jr. from Everett AquaSox. |
| 06/15/26 | Seattle Mariners traded RHP Yosver Zulueta to Chicago Cubs for cash. |
| 06/15/26 | Seattle Mariners sent RHP Domingo Gonzalez outright to Tacoma Rainiers. |
| 06/15/26 | Seattle Mariners optioned 3B Patrick Wisdom to Tacoma Rainiers. |
| 06/14/26 | Seattle Mariners signed free agent 3B Weston Wilson to a minor league contract. |
| 06/13/26 | Seattle Mariners signed free agent LHP Michael Plassmeyer to a minor league contract. |
| 06/12/26 | Seattle Mariners acquired RHP Connor Wilford from the Lexington Legends of the Atlantic League. |
| 06/11/26 | Seattle Mariners designated RHP Domingo Gonzalez for assignment. |
| 06/11/26 | Seattle Mariners selected the contract of RHP Michael Rucker from Tacoma Rainiers. |
| 06/10/26 | Seattle Mariners activated 3B Miles Mastrobuoni from the 60-day injured list. |
| 06/10/26 | Seattle Mariners placed RHP Matt Brash on the 15-day injured list retroactive to June 9, 2026. Right lat strain. |
| 06/10/26 | Seattle Mariners designated RHP Yosver Zulueta for assignment. |
| 06/10/26 | Seattle Mariners optioned 2B Ryan Bliss to Tacoma Rainiers. |
| 06/10/26 | Pittsburgh Pirates traded RHP Carson Fulmer to Seattle Mariners for cash. |
| 06/10/26 | Seattle Mariners recalled RHP Domingo Gonzalez from Tacoma Rainiers. |
| 06/09/26 | Seattle Mariners placed RHP Cooper Criswell on the 15-day injured list. Right shoulder strain. |
| 06/09/26 | Seattle Mariners sent C Cal Raleigh on a rehab assignment to Tacoma Rainiers. |
| 06/09/26 | Seattle Mariners sent 3B Will Wilson on a rehab assignment to Tacoma Rainiers. |
| 06/09/26 | Seattle Mariners recalled RHP Nick Davila from Tacoma Rainiers. |
| 06/08/26 | Seattle Mariners placed SS J.P. Crawford on the 10-day injured list retroactive to June 6, 2026. Right hand contusion. |
| 06/08/26 | Seattle Mariners recalled 2B Ryan Bliss from Tacoma Rainiers. |
| 06/07/26 | Seattle Mariners sent C Cal Raleigh on a rehab assignment to Everett AquaSox. |
| 06/05/26 | Seattle Mariners signed free agent SS Magz German to a minor league contract. |
| 06/05/26 | Seattle Mariners sent 3B Will Wilson on a rehab assignment to Everett AquaSox. |
| 06/04/26 | Seattle Mariners signed free agent LHP Caleb Franzen to a minor league contract. |