The Flyers overcame a shaky start by goalie Steve Mason and played one of their best offensive games of the season Tuesday.
It wasn't enough.
Kyle Okposo scored the only goal in the shootout, lifting the Islanders to a 4-3 win at the Wells Fargo Center.
Jaroslav Halak made 43 saves for the Isles, and he also denied Claude Giroux, Wayne Simmonds, and Evgeny Medvedev in the shootout.
The Flyers outshot the Islanders, 46-26. Giroux had seven of the shots.
"We played the way we want to play," said Giroux, who had a goal, an assist, and won 63 percent of his faceoffs. "We were pretty consistent, but when you don't get the two points, it's not a good feeling."
Flyers goalie Michal Neuvirth made the best save in the overtime, stopping Nick Leddy in front with 21 seconds left.
After relieving Mason early in the second period, Neuvirth stopped all 16 shots he faced, including Casey Cizikas' breakaway. He lowered his goals-against average to 1.99 and raised his save percentage to .937. Both figures are second in the NHL among goalies with at least 10 appearances.
With 9:17 left in the third, Halak made his 40th and perhaps best save of the night. Sitting down on the ice during a scramble, Halak stopped Pierre-Edouard Bellemare on a rebound that would have given the Flyers their first lead.
Giroux tied it at 3-3 just 2:02 into the third period, scoring on a one-timer from above the right circle. The shot deflected off Leddy in front of the net.
Earlier, the Flyers appeared to tie the game at 3-all when Simmonds scored on a rebound with 6:07 to play in the second period. But the power-play goal was erased when the video review determined that Simmonds used a distinct kicking motion to score.
"I didn't kick it," Simmonds said. "I just put my foot down to stop it, but it's not my decision, obviously; it's their decision."
The Flyers had gotten to within 3-2 about 10 minutes earlier on Ryan White's second goal of the season. White scored about three minutes after Mason was replaced by Neuvirth.
Taking a nice feed from a patient R.J. Umberger, White beat Halak from the slot with 15:51 left in the second.
Mason, winless in his last seven home starts, went to the bench after Frans Nielsen's second goal of the night. Nielsen scored from above the right circle, firing a shot that went between the legs of on-charging defenseman Michael Del Zotto and beat Mason to the glove side 1:14 into the second period.
"Three goals on 10 shots isn't good....I have to be better," Mason said.
Mason, who hasn't won at home since a 3-2 shootout victory over the New York Rangers on Oct. 24, also allowed an early goal in the opening period.
Fifty-five seconds into the game, Nielsen got behind defenseman Nick Schultz and finished off a two-on-one, scoring on the Isles' first shot of the night.
The Flyers tied it on a rare two-on-none that produced a shorthanded goal - Bellemare knocking in a pretty pass from Giroux with 11:48 left in the first period.
"I was just waiting to see if he was going to give it back to me," said Bellemare about the give-and-go, "and he did and the goalie was gone."
But on the same power play, the Islanders made it 2-1 as Brock Nelson - who played for Flyers coach Dave Hakstol at North Dakota - tipped in Leddy's one-time blast from the point. Mason appeared screened by Bellemare.
The Flyers were coming off a listless 4-1 home loss to Columbus on Saturday, a defeat that ended their four-game winning streak.
They rebounded impressively on Tuesday, outplaying a speedy Islanders team that is on a 6-0-2 run, and recording a season-high 89 shots attempts to the visitors' 51.
"I thought from start to finish, we were the better team," Simmonds said. "We didn't come out with the two points, but sometimes that happens."