Mariners Roster & Staff
Transactions
| Date | Transaction |
| 08/28/19 | Seattle Mariners sent RHP Brandon Brennan on a rehab assignment to Tacoma Rainiers. |
| 08/26/19 | Seattle Mariners sent RHP Austin Adams on a rehab assignment to Arkansas Travelers. |
| 08/24/19 | Seattle Mariners activated RHP Felix Hernandez from the 60-day injured list. |
| 08/24/19 | Seattle Mariners optioned RHP Zac Grotz to Tacoma Rainiers. |
| 08/23/19 | Seattle Mariners recalled LHP Justus Sheffield from Arkansas Travelers. |
| 08/23/19 | New York Yankees claimed RHP Cory Gearrin off waivers from Seattle Mariners. |
| 08/23/19 | Seattle Mariners recalled P Justus Sheffield. |
| 08/23/19 | Seattle Mariners sent OF Braden Bishop on a rehab assignment to Tacoma Rainiers. |
| 08/23/19 | Seattle Mariners recalled P Justus Sheffield. |
| 08/23/19 | Seattle Mariners recalled LHP Justus Sheffield. |
| 08/23/19 | Seattle Mariners recalled P Justus Sheffield. |
| 08/22/19 | Seattle Mariners sent RHP Austin Adams on a rehab assignment to Tacoma Rainiers. |
| 08/20/19 | Seattle Mariners sent RF Mitch Haniger on a rehab assignment to Tacoma Rainiers. |
| 08/20/19 | Seattle Mariners placed LF Domingo Santana on the 10-day injured list retroactive to August 19, 2019. Right elbow inflammation. |
| 08/20/19 | Seattle Mariners selected the contract of Jake Fraley from Tacoma Rainiers. |
| 08/19/19 | Seattle Mariners signed free agent C Geury Pena to a minor league contract. |
| 08/18/19 | Seattle Mariners sent RHP Felix Hernandez on a rehab assignment to Tacoma Rainiers. |
| 08/17/19 | Seattle Mariners signed free agent RHP Steven Sanchez to a minor league contract. |
| 08/15/19 | Seattle Mariners placed RHP Brandon Brennan on the 10-day injured list retroactive to August 14, 2019. Right shoulder inflammation. |
| 08/15/19 | Seattle Mariners sent RHP Dan Altavilla on a rehab assignment to Tacoma Rainiers. |
| 08/15/19 | Seattle Mariners selected the contract of Taylor Guilbeau from Tacoma Rainiers. |
| 08/14/19 | Seattle Mariners sent RHP Felix Hernandez on a rehab assignment to Everett AquaSox. |
| 08/13/19 | Seattle Mariners sent RF Mitch Haniger on a rehab assignment to Modesto Nuts. |
| 08/13/19 | Seattle Mariners sent CF Braden Bishop on a rehab assignment to Modesto Nuts. |
| 08/12/19 | Seattle Mariners signed free agent RHP Brendan McGuigan to a minor league contract. |
| 08/11/19 | Seattle Mariners sent RHP Dan Altavilla on a rehab assignment to Everett AquaSox. |
| 08/10/19 | Seattle Mariners activated 2B Dee Strange-Gordon from the 10-day injured list. |
| 08/10/19 | Seattle Mariners optioned SS Ryan Court to Tacoma Rainiers. |
| 08/10/19 | Seattle Mariners signed free agent RHP Leo Rodriguez to a minor league contract. |
| 08/10/19 | Seattle Mariners traded CF Ian Miller to Minnesota Twins for cash. |
| 08/09/19 | Seattle Mariners traded C Jose Lobaton to Los Angeles Dodgers for cash. |
| 08/08/19 | Seattle Mariners sent RHP Felix Hernandez on a rehab assignment to Modesto Nuts. |
| 08/06/19 | Seattle Mariners activated RHP Brandon Brennan from the 10-day injured list. |
| 08/06/19 | Seattle Mariners optioned RHP Gerson Bautista to Tacoma Rainiers. |
| 08/06/19 | Detroit Tigers claimed RHP David McKay off waivers from Seattle Mariners. |
| 08/06/19 | Tim Lopes roster status changed by Seattle Mariners. |
| 08/06/19 | Seattle Mariners placed SS Tim Beckham on the restricted list. |
| 08/05/19 | Seattle Mariners placed 2B Tim Lopes on the 10-day injured list. Concussion. |
| 08/02/19 | Seattle Mariners sent RHP Felix Hernandez on a rehab assignment to Everett AquaSox. |
| 08/02/19 | Seattle Mariners selected the contract of RHP Reggie McClain from Tacoma Rainiers. |
| 08/02/19 | Seattle Mariners sent 2B Tim Lopes on a rehab assignment to Tacoma Rainiers. |
| 08/01/19 | Seattle Mariners signed free agent RHP Brian Ellington to a minor league contract. |
| 08/01/19 | Seattle Mariners signed free agent RHP Kristian Cardozo to a minor league contract. |