Mariners Roster & Staff
Transactions
| Date | Transaction |
| 03/31/26 | Seattle Mariners designated RHP Ryan Loutos for assignment. |
| 03/31/26 | Seattle Mariners sent SS J.P. Crawford on a rehab assignment to Tacoma Rainiers. |
| 03/31/26 | Seattle Mariners sent SS J.P. Crawford on a rehab assignment to Tacoma Rainiers. |
| 03/31/26 | Seattle Mariners selected the contract of SS Colt Emerson from Tacoma Rainiers. |
| 03/27/26 | RHP Adam Maier roster status changed by Seattle Mariners. |
| 03/27/26 | Seattle Mariners signed free agent RHP Chase Centala to a minor league contract. |
| 03/27/26 | Seattle Mariners placed RHP Carlos Vargas on the 15-day injured list retroactive to March 24, 2026. Right lat strain. |
| 03/27/26 | Seattle Mariners recalled RHP Cole Wilcox from Tacoma Rainiers. |
| 03/26/26 | Seattle Mariners signed free agent RHP Adam Maier to a minor league contract. |
| 03/26/26 | RHP Cooper Criswell changed number to 88. |
| 03/25/26 | Seattle Mariners placed 3B Miles Mastrobuoni on the 10-day injured list retroactive to March 22, 2026. Right calf strain. |
| 03/25/26 | Seattle Mariners released C Andrew Knizner. |
| 03/25/26 | Seattle Mariners placed RHP Bryce Miller on the 15-day injured list retroactive to March 22, 2026. Left oblique strain. |
| 03/25/26 | Seattle Mariners placed SS J.P. Crawford on the 10-day injured list retroactive to March 22, 2026. Right shoulder inflammation. |
| 03/25/26 | Seattle Mariners selected the contract of C Mitch Garver from Tacoma Rainiers. |
| 03/25/26 | Seattle Mariners optioned RHP Alex Hoppe to Tacoma Rainiers. |
| 03/24/26 | Seattle Mariners designated C Andrew Knizner for assignment. |
| 03/24/26 | Seattle Mariners signed free agent RHP Will Armbruester to a minor league contract. |
| 03/23/26 | SS Leandro Romero assigned to Seattle Mariners. |
| 03/23/26 | RHP Casey Hintz assigned to Seattle Mariners. |
| 03/23/26 | 2B Brady O'Brien assigned to Seattle Mariners. |
| 03/22/26 | CF Cesar Quintas assigned to Seattle Mariners. |
| 03/22/26 | 2B Ricardo Cova assigned to Seattle Mariners. |
| 03/22/26 | Seattle Mariners optioned C Jhonny Pereda to Tacoma Rainiers. |
| 03/22/26 | Seattle Mariners optioned RHP Yosver Zulueta to Tacoma Rainiers. |
| 03/22/26 | Seattle Mariners optioned RHP Cole Wilcox to Tacoma Rainiers. |
| 03/21/26 | Seattle Mariners optioned LF Rhylan Thomas to Tacoma Rainiers. |
| 03/20/26 | Seattle Mariners released RHP Guillo Zuñiga. |
| 03/19/26 | RHP Jose Geraldo assigned to Seattle Mariners. |
| 03/17/26 | RHP Gunner Mayer assigned to Seattle Mariners. |
| 03/17/26 | CF George Feliz assigned to Seattle Mariners. |
| 03/17/26 | OF Brayden Corn assigned to Seattle Mariners. |
| 03/15/26 | OF Konni Durschlag assigned to Seattle Mariners. |
| 03/14/26 | RHP Wyatt Lunsford-Shenkman assigned to Seattle Mariners. |
| 03/14/26 | OF Ryan Picollo assigned to Seattle Mariners. |
| 03/14/26 | Seattle Mariners optioned LHP Robinson Ortiz to Tacoma Rainiers. |
| 03/13/26 | LHP Jacob Denner assigned to Seattle Mariners. |
| 03/13/26 | OF Anthony Donofrio assigned to Seattle Mariners. |
| 03/13/26 | Seattle Mariners optioned RHP Troy Taylor to Tacoma Rainiers. |
| 03/13/26 | Seattle Mariners optioned LHP Josh Simpson to Tacoma Rainiers. |
| 03/12/26 | OF Aiden Taurek assigned to Seattle Mariners. |
| 03/11/26 | CF Curtis Washington Jr. assigned to Seattle Mariners. |
| 03/11/26 | Seattle Mariners optioned RHP Blas Castaño to Tacoma Rainiers. |
| 03/11/26 | Seattle Mariners optioned RHP Domingo Gonzalez to Tacoma Rainiers. |
| 03/10/26 | SS Carter Dorighi assigned to Seattle Mariners. |
| 03/08/26 | Seattle Mariners optioned RHP Ryan Loutos to Tacoma Rainiers. |
| 03/07/26 | 2B Alejo Lopez assigned to Seattle Mariners. |
| 03/07/26 | C Grant Jay assigned to Seattle Mariners. |
| 03/07/26 | 2B Josh Hood assigned to Seattle Mariners. |
| 03/06/26 | C Matthew Ellis assigned to Seattle Mariners. |
| 03/06/26 | OF Korbyn Dickerson assigned to Seattle Mariners. |
| 03/05/26 | SS Axel Sanchez assigned to Seattle Mariners. |
| 03/05/26 | C Aaron McKeithan assigned to Seattle Mariners. |
| 03/05/26 | LF Colin Davis assigned to Seattle Mariners. |
| 03/04/26 | 1B Hogan Windish assigned to Seattle Mariners. |
| 03/03/26 | C Connor Dykstra assigned to Seattle Mariners. |
| 03/03/26 | C Mitch Garver assigned to Seattle Mariners. |
| 03/01/26 | OF Bill Knight roster status changed by Seattle Mariners. |
| 03/01/26 | OF Bill Knight assigned to Seattle Mariners. |
| 03/01/26 | Seattle Mariners signed free agent C Jacob Nottingham to a minor league contract. |