Sebastian Giovinco scored a 95th-minute winning goal to conclude another wild affair between the two rivals and deliver the Reds their sixth Canadian Championship.
The Italian converted from a Raheem Edwards cross from close range not long after being denied a stonewall penalty in a game that was, to say the least, controversially refereed.
Toronto were fuming about a reckless Kyle Fisher challenge on Steven Beitashour on the stroke of half-time and the denial of what appeared to be a stonewall penalty for another Fisher challenge on Giovinco after the break.
After Patrice Bernier had been sent off for a high tackle on Marky Delgado in the 89th minute, though, the Reds made the most of the man advantage they possessed in the closing stages. Giovinco’s second of the night made it 2-1, sealing a 3-2 aggregate victory.
Giovinco had equalized earlier in the second half after Ballou Jean-Yves Tabla gave Montreal the lead with a sublime 25-yard effort.
Toronto dominated the first half and went closest when Maxime Crepeau produced a stunning one-handed save to push away a Tosaint Ricketts header.
But the Impact, as they have made a habit of doing against Toronto, took the lead against the run of play. Chris Mavinga appeared to have stopped a counter-attack in its tracks with a sliding tackle but the ball squirted loose to Blerim Dzemaili, who laid it off for Ballou to curl a superb left-footed shot into the top corner.
That goal knocked the stuffing out of the Reds and Greg Vanney reacted at half-time by introducing Marky Delgado and Jozy Altidore for Jonathan Osorio and Ricketts.
It worked, with Delgado keeping an attack alive to allow Michael Bradley to pick out Giovinco with a pass floated into the box. The Italian brought it under control, cut inside and swept a low, left-footed effort past Crepeau.
In the final half hour, chaos ensued. Fisher should have been dismissed for a sliding challenge on Giovinco in the box that was somehow not whistled for a penalty by Canadian referee David Gantar.
Bernier was dismissed for a challenge that did not look as dangerous as Fisher’s on Beitashour in the first half before Giovinco claimed the night, the trophy and CONCACAF Champions League football next season.