Mariners Roster & Staff
Transactions
| Date | Transaction |
| 06/28/15 | Seattle Mariners signed RHP Matt Walker. |
| 06/27/15 | Seattle Mariners signed 1B Dalton Kelly. |
| 06/25/15 | Seattle Mariners sent RHP Hisashi Iwakuma on a rehab assignment to Tacoma Rainiers. |
| 06/24/15 | Seattle Mariners signed CF Ricky Eusebio. |
| 06/24/15 | Seattle Mariners selected the contract of LF Franklin Gutierrez from Tacoma Rainiers. |
| 06/24/15 | Seattle Mariners optioned CF James Jones to Tacoma Rainiers. |
| 06/21/15 | Seattle Mariners released LF Rickie Weeks. |
| 06/21/15 | 1B Conner Hale assigned to Seattle Mariners. |
| 06/20/15 | Seattle Mariners sent RHP Hisashi Iwakuma on a rehab assignment to Everett AquaSox. |
| 06/17/15 | Seattle Mariners signed RHP Dylan Thompson. |
| 06/17/15 | Seattle Mariners signed LHP Dylan Silva. |
| 06/16/15 | Seattle Mariners signed 1B Rob Fonseca. |
| 06/16/15 | Seattle Mariners signed RHP Joe Peeler. |
| 06/16/15 | Seattle Mariners signed RHP Ljay Newsome. |
| 06/16/15 | Seattle Mariners signed RHP Michael Rivera. |
| 06/16/15 | Seattle Mariners signed RHP Gianni Zayas. |
| 06/16/15 | Seattle Mariners signed SS Julius Gaines. |
| 06/16/15 | Seattle Mariners signed OF Augustus Craig. |
| 06/16/15 | Seattle Mariners signed LHP Jared West. |
| 06/16/15 | Seattle Mariners signed SS Taylor Perez. |
| 06/16/15 | Seattle Mariners signed RHP Nick Neidert. |
| 06/16/15 | Seattle Mariners signed RHP Cody Mobley. |
| 06/16/15 | Seattle Mariners signed RHP Jio Orozco. |
| 06/16/15 | Seattle Mariners signed RHP Ryne Inman. |
| 06/16/15 | Seattle Mariners signed RHP Joey Strain. |
| 06/15/15 | Seattle Mariners signed RHP Darin Gillies. |
| 06/15/15 | Seattle Mariners signed LHP Logan James. |
| 06/15/15 | Seattle Mariners signed LHP Matt Clancy. |
| 06/15/15 | Seattle Mariners recalled James Jones from Tacoma Rainiers. |
| 06/15/15 | Seattle Mariners optioned RHP Danny Farquhar to Tacoma Rainiers. |
| 06/15/15 | Seattle Mariners signed OF Braden Bishop. |
| 06/15/15 | Seattle Mariners signed LHP Anthony Misiewicz. |
| 06/15/15 | Seattle Mariners signed RHP Andrew Moore. |
| 06/15/15 | Seattle Mariners signed LHP Joseph Pistorese. |
| 06/15/15 | Seattle Mariners signed RHP Colin Tornberg. |
| 06/15/15 | Seattle Mariners signed RHP Arthur Warren. |
| 06/15/15 | Seattle Mariners signed RHP Kyle Wilcox. |
| 06/15/15 | Seattle Mariners signed C Patrick Jones. |
| 06/15/15 | Seattle Mariners signed SS Drew Jackson. |
| 06/15/15 | Seattle Mariners signed LF Logan Taylor. |
| 06/15/15 | Seattle Mariners signed 1B Ryan Uhl. |
| 06/15/15 | Seattle Mariners signed RHP Lance Thonvold. |
| 06/13/15 | Seattle Mariners sent OF Justin Ruggiano outright to Tacoma Rainiers. |
| 06/13/15 | Seattle Mariners recalled Danny Farquhar from Tacoma Rainiers. |
| 06/13/15 | Seattle Mariners designated LF Rickie Weeks for assignment. |
| 06/08/15 | Seattle Mariners signed free agent 2B Tyler Bortnick to a minor league contract. |
| 06/04/15 | Seattle Mariners designated Justin Ruggiano for assignment. |
| 06/04/15 | Seattle Mariners recalled C Jesus Sucre from Tacoma Rainiers. |
| 06/04/15 | Seattle Mariners activated RF Mark Trumbo. |
| 06/04/15 | Vidal Nuno roster status changed by Seattle Mariners. |
| 06/03/15 | Seattle Mariners signed free agent RHP Kyle Schepel to a minor league contract. |
| 06/03/15 | Arizona Diamondbacks traded RF Mark Trumbo and LHP Vidal Nuno to Seattle Mariners for C Welington Castillo, RHP Dominic Leone, RF Gabriel Guerrero and SS Jack Reinheimer. |
| 06/03/15 | Arizona Diamondbacks traded RF Mark Trumbo and LHP Vidal Nuno to Seattle Mariners for C Welington Castillo, RHP Dominic Leone, RF Gabriel Guerrero and SS Jack Reinheimer. |
| 06/03/15 | Arizona Diamondbacks traded RF Mark Trumbo and LHP Vidal Nuno to Seattle Mariners for C Welington Castillo, RHP Dominic Leone, RF Gabriel Guerrero and SS Jack Reinheimer. |
| 06/03/15 | Arizona Diamondbacks traded RF Mark Trumbo and LHP Vidal Nuno to Seattle Mariners for C Welington Castillo, RHP Dominic Leone, RF Gabriel Guerrero and SS Jack Reinheimer. |
| 06/03/15 | Arizona Diamondbacks traded RF Mark Trumbo and LHP Vidal Nuno to Seattle Mariners for C Welington Castillo, RHP Dominic Leone, RF Gabriel Guerrero and SS Jack Reinheimer. |
| 06/03/15 | Arizona Diamondbacks traded RF Mark Trumbo and LHP Vidal Nuno to Seattle Mariners for C Welington Castillo, RHP Dominic Leone, RF Gabriel Guerrero and SS Jack Reinheimer. |
| 06/02/15 | Seattle Mariners optioned LHP Tyler Olson to Tacoma Rainiers. |
| 06/02/15 | Seattle Mariners optioned RHP Mayckol Guaipe to Tacoma Rainiers. |
| 06/02/15 | Seattle Mariners recalled Mike Montgomery from Tacoma Rainiers. |
| 06/01/15 | Seattle Mariners recalled Mayckol Guaipe from Tacoma Rainiers. |
| 06/01/15 | Seattle Mariners optioned SS Chris Taylor to Tacoma Rainiers. |