It was the first grand slam of Suzuki's career.
Down to their last out, the Mariners stroked three straight hits to deal Mike MacDougal (3-4) his sixth blown save of the season.
Edgar Martinez opened the ninth with a walk and moved to second one out later on a bloop single by Ben Davis, who fouled off four pitches before his hit.
Randy Winn struck out, but Willie Bloomquist singled to load the bases and pinch hitter John Mabry drilled a one-hopper off MacDougal's leg, bringing in Martinez to make it 3-2 and bringing up Suzuki.
Suzuki's homer was the ninth of the season, a career high.