Ovechkin, who scored 14 goals in his prior seven games, remained two goals from becoming the eighth NHL player to score 700.
"It was not a good night," Washington coach Todd Reirden said. "So it's up to us to get away from the rink tomorrow and be back ready to play another Metropolitan Division] opponent and see what our response is."
***[WATCH: [All Flyers vs. Capitals highlights]*
Ovechkin, who had two shots on goal, will try again for 700 on Monday against the New York Islanders.
Claude Giroux reached 800 NHL points with a goal and two assists for the Flyers (30-18-7), who are 7-2-1 in their past nine games.
"The win feels the best, especially when you come to a building that's really tough to play in, and I haven't been playing that great lately," said Giroux, who had not scored a goal in 13 games. "It's good to be able to contribute to a team win and we have to keep it going."
Brian Elliott made 25 saves for Philadelphia, which lost to the New Jersey Devils 5-0 on Thursday.
"There's no doubt that our guys were highly motivated, but I think we were motivated against the Devils. Tonight, the difference was we were able to capitalize on some of our looks," Flyers coach Alain Vigneault said. "We had the saves at the right time. But go figure it out: We were able to put seven tonight and we weren't able to put one last game."
T.J. Oshie and Evgeny Kuznetsov scored for the Capitals (36-14-5), who are 2-3-0 in their past five games. Braden Holtby was pulled after allowing seven goals on 25 shots. Ilya Samsonov made one save in the final 11:58.
"In all areas, we lost every aspect of the game tonight," Reirden said. "And when you're going to do that in this league against a divisional opponent, then you're not going to have success."
The Flyers took a 1-0 lead on Sean Couturier's power-play goal at 15:22 of the first period. Giroux carried the puck behind the net and passed to Couturier, who scored with a one-timer from the left circle.