Philadelphia won its seventh straight after hearing that team captain Chris Pronger would be lost for the rest of the season due to a concussion.
The Flyers never trailed, but during the first two periods each of Philadelphia's three goals was answered by one from the Canadiens.
Montreal could not respond, however, to a slap shot from Meszaros that eluded Carey Price 8:08 into the final period. The Canadiens had won their previous two games.
Sergei Bobrovsky got the win by stopping 28-of-31 shots. Philadelphia moved two points in front of idle Boston for the best record in the Eastern Conference.
Price made 25 saves and suffered his first loss since Nov. 25.