The Mariners faced a 3-1 deficit heading into the ninth but they loaded the bases against Kevin Gregg (0-1) with two singles and a walk. Another walk to Casey Kotchman produced the first run of the inning and Josh Bard tied the contest with a sacrifice fly.
Griffey then came up as a pinch hitter and his smash to right field, which was scored a single, easily brought in Milton Bradley with the winning run.
Shawn Kelley (2-0) picked up the victory in relief of Jason Vargas. The Mariners halted a five-game losing streak.
Jose Bautista hit a two-run homer for Toronto, which had won six of its previous seven.