Toronto avenged a penalty-shootout loss to Seattle last year in the title game and completed the domestic treble on home soil at the BMO Field, Toronto.
The Canadian side finished 12 points clear of New York in the Eastern Conference heading into the play-offs and edged past Seattle with Vazquez striking in the fourth minute of added time in off the post.
It appeared to be Toronto’s title to lose throughout with the Canadian side out shooting Seattle 22-7 and had 11 shots on target compared to two for the Sounders.
After going without a shot on goal in last year’s MLS Cup, Seattle struggled to find the target in the opening 30 minutes Saturday, finally ending its dubious streak when defender Joevin Jones fired a tame effort into the arms of goalkeeper Alex Bono.
Toronto’s dominance showed and they looked certain to open the scoring in the 11th minute when a long, accurate pass from Vasquez found Sebastian Giovinco alone in the penalty box, but the 2015 MLS MVP’s chip over a sliding Stefan Frei rolled wide.
In the 23rd minute, shortly after he blasted a 30-yard free kick directly into the Seattle wall, Giovinco got loose inside the 18-yard box and unleashed a hard, left-footed shot that Frei managed to palm over for a corner.
Seattle’s Joevin Jones was fortunate not to put the ball into his own net when he cleared Justin Morrow’s shot along the goal line just before halftime. The Trinidadian defender, who is set to move to Germany’s Darmstadt 98 next season, managed to steer the ball behind the goal for a corner.
Toronto came close again in the 41st minute when Vasquez blasted a low shot across goal from outside the penalty box, but Frei dove to his right to push the ball to safety, with both sides going into the break goalless.
The tension continued to flow through the game following the restart, but for all their dominance, Toronto found the breakthrough after Giovinco’s pass from just inside the Seattle half helped Altidore split a pair of defenders.
Altidore took a few steps to his left and fired the ball over goalkeeper Frei, setting off a wild celebration among the 30,000 fans that left BMO Field shaking.
The American scored in Toronto’s 1-0 victory over Columbus Crew in the Eastern Conference final and had scored 15 goals in the regular season heading into the play offs second to Giovinco’s 16.
Altidore, who injured his right ankle minutes after scoring against the Crew, was replaced by Nick Hagglund in the 86th minute, before Vazquez confirmed the win minutes later to silence Seattle for good.