The left-handed Washburn (5-9) allowed a run and scattered four hits. J.J. Putz tossed a scoreless ninth.
The Mariners, trailing 1-0, surged ahead with a four-run sixth inning, highlighted by Vidro's home over the left field wall.
Toronto's John McDonald hit his first home run of the year, a shot to left in the fifth.
Losing pitcher Shaun Marcum (5-5) worked 5 2/3 innings, giving up four runs and six of Seattle's 11 hits.
The Blue Jays had won their five previous games.