Melky Cabrera led off the 11th to hit the game-winning home run. Cabrera belted a 2-1 pitch over the right field wall for the Yankees' ninth win in their last at-bat.
Pitcher Scott Proctor (3-2) picked up the win with a hitless inning.
The Yankees have won five in a row and nine of their last 10 games.
Seattle manager Mike Hargrove was then ejected from the game after Jorge Posada was called safe on an infield grounder to Jose Lopez at second. Replays show his throw beat Posada by half a step, but first base umpire Mike Reilly called him safe and kept the Yankee rally alive. Damon followed with a sac fly to center to tie the game at four.
The game was suspended for almost two hours because of rain.