Ovechkin's second-period tally was his 16th in 13 games and ninth in nine road contests for the Caps, who retained their four-point lead over Winnipeg atop the Southeast Division.
Jack Hillen's first goal of the season gave a Washington a 3-1 third-period lead and proved to be the game-winner.
Eric Fehr also found the net as the Caps reeled off their fifth straight victory.
Michal Neuvirth earned the win with 27 saves.
Lars Eller netted both goals for the Northeast Division-leading Canadiens.
Carey Price stopped 24 shots in the loss.