Mariners Roster & Staff
Transactions
| Date | Transaction |
| 12/16/25 | Seattle Mariners signed free agent C Andrew Knizner. |
| 12/10/25 | Seattle Mariners purchased contract of RHP Sean Hermann in the Rule 5 Draft, AAA Phase. |
| 12/10/25 | Milwaukee Brewers purchased contract of RHP Cole Phillips in the Rule 5 Draft, AAA Phase. |
| 12/10/25 | Seattle Mariners purchased contract of 1B Carson Taylor in the Rule 5 Draft, AAA Phase. |
| 12/06/25 | Washington Nationals traded LHP Jose A. Ferrer to Seattle Mariners for C Harry Ford and RHP Isaac Lyon. |
| 12/06/25 | Washington Nationals traded LHP Jose A. Ferrer to Seattle Mariners for C Harry Ford and RHP Isaac Lyon. |
| 12/06/25 | Washington Nationals traded LHP Jose A. Ferrer to Seattle Mariners for C Harry Ford and RHP Isaac Lyon. |
| 12/05/25 | C Harry Ford roster status changed by Seattle Mariners. |