Jakub Voracek and Wayne Simmonds added goals, and Steve Mason made 32 saves to help Philadelphia improve to 12-2-1 in its last 15 games to maintain its hold on second place in the Metropolitan Division.
Jaden Schwartz opened the scoring 6:23 into the game, finishing a 2-on-1 short-handed opportunity after taking a feed from Kevin Shattenkirk. Schwartz's wrist shot from close range went under the glove of Mason.
St. Louis needed one point in the game to become the first Western Conference team to clinch a playoff spot.
If you want to prove people wrong, you've just got to go out and do it. Yeah, we blew 3-2 series leads the last two years, but no one is going remember that if we go out there on Saturday night and beat these guys and go play in the Stanley Cup Final. We need to get back to work and we'll start to do that tomorrow.
— Ducks forward Kyle Palmieri following a loss to the Blackhawks in Game 6 on Wednesday