Flyers goaltender Petr Mrazek stopped 25 shots.
Alex Ovechkin, Chandler Stephenson and John Carlson each scored for the Capitals, who had their four-game winning streak snapped.
Washington goaltender Philipp Grubauer was very shaky all night and made only 29 saves on 34 shots.
Just 1:37 into the third period, Simmonds extended Philadelphia's lead to 4-1. Simmonds redirected the puck into the net for a commanding three-goal advantage.
Stephenson cut the lead in half with his first goal in 17 games, with Jakub Vrana getting the assist at 10:31.
Simmonds struck again at 14:27, and the three-goal cushion was more than enough.
Gostisbehere gave the Flyers a 1-0 lead at 2:15 of the second period with his 12th goal of the season. Claude Giroux picked up the assist and registered his 659th career point, tying him for fifth place in Flyers history with Eric Lindros.
Sean Couturier (two assists) nearly gave the Flyers a 2-0 lead with 10:07 left but was denied with a solid save by Grubauer. Less than a minute later, Couturier had two more shots, both of which were stopped by Grubauer.
Mrazek kept the shutout intact with a pair of dazzling saves late in the second.
Washington's relentless pressure paid off as it tied the game at 1 with 4:42 remaining in the middle period when Ovechkin deflected a shot past Mrazek for his 43rd goal of the season.
Lindblom put the Flyers ahead 2-1 with 1:41 left in the second thanks in large part to Voracek's 60th assist of the season. It was Lindblom's first career goal.
The Flyers weren't done as Provorov scored with just 18.3 seconds in the second remaining for a 3-1 advantage. The puck seemed to get misdirected and fool Grubauer.
--Field Level Media
Washington | Philadelphia | |
John Carlson 2 | Points | Wayne Simmonds 2 |
John Carlson 1 | Goals | Wayne Simmonds 2 |
John Carlson 1 | Assists | Sean Couturier 2 |
N/A | Power Play Goals | N/A |
N/A | Short Handed Goals | N/A |
Philipp Grubauer .853 | Save Percentage | Petr Mrazek .893 |
Philipp Grubauer 29 | Saves | Petr Mrazek 25 |
Team | Shots | Goals | Power Play | Penalty Kill | Penalty Mins | Face Offs Won |
Washington | 28 | 3 | 0-3 | 3-3 | 13 | 33 |
Philadelphia | 35 | 6 | 0-3 | 3-3 | 13 | 25 |