The hosts were in control for the majority of the contest but wasted a number of good chances in the first half.
Daniele Paponi headed over from close range midway through the first period, before Jeb Brovsky sliced a shot wide of the target just minutes later.
Montreal broke the deadlock in the 57th minute when Andres Romero collected the ball in space inside the box before curling a superb shot into the top corner to leave Sean Johnson helpless in the Chicago goal.
Chicago's hopes of claiming a point were dealt a blow when they were reduced to 10 men, with Jeff Larentowicz given his marching orders for an ugly tackle on Andrea Pisanu.
Montreal took advantage of the numerical advantage to double their lead and wrap up the victory in the 76th minute, thanks to a smart finish from Marco Di Vaio.