Chris Pronger had four assists and Sergei Bobrovsky made 29 saves for the Flyers, who improved to 10-2-0 in January with the 1,000th home victory in franchise history.
Mathieu Darche and David Desharnais scored for Montreal and Carey Price surrendered four goals in 34 shots on goal. The Habs are winless in their past four games.
Carter and Timonen staked the Flyers to a 2-0 first-period lead. Daniel Carcillo made it 3-0 with a backhander 23 seconds into the second period.
After Desharnais made it 3-1 at 12:43 of the second, Giroux scored on a power play that put the Flyers ahead 4-1 after two periods.
The two teams traded goals in the third, with Darche scoring at 15:17 and Danny Briere knocking in an empty-netter for Philadelphia in the closing seconds.