Trevor Moore, with a goal and an assist, and John Tavares also scored for Toronto. Mitch Marner added two assists.
Keith Kinkaid stopped 46 shots for Montreal.
Toronto took the ice just over 24 hours after news broke that Matthews is facing a charge of disorderly conduct and disruptive behaviour stemming from an alleged incident in his hometown of Scottsdale, Ariz., back in May.
WATCH| Leafs top Canadiens in pre-season action:
The 22-year-old centre made a brief statement to an unusually large contingent of reporters for a pre-season game at Wednesday’s the morning skate, but didn’t take any questions.
Matthews, who played with regular linemates William Nylander and Andreas Johnsson, scored on a third-period power play off a great feed from Marner.