Biron made 38 saves and has beaten the Islanders 10 straight times. He made a brilliant glove save on Jack Hillen late in the first period. He also thwarted a breakaway attempt by Sean Bergenheim late in the second period.
It was Biron's first win since he beat Toronto 4-1 on Jan. 10. Since then he was 0-4, allowing 17 goals in 13 periods before Saturday.
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Biron was lifted in his last start after allowing three goals in the first period at Boston on Feb. 7 in a game won by the Flyers 4-3.
The Flyers scored twice within 44 seconds early in the first period and added two other goals within 13 seconds midway through the third.
Giroux put the Flyers ahead with a one-timer at 5:00 of the first period after taking a pass from Upshall.
Hartnell made it 2-0 when he deflected Jeff Carter's wrist shot from the right circle at 5:44.
Andy Hilbert scored the only goal for the Islanders, who dropped their fifth straight game. Hilbert got the Islanders within 2-1 with a wrist shot from the top of the left circle at 6:15 of the third period.
Carle scored unassisted at 9:10, Asham was credited with a goal when the puck nicked off his skate at 9:23, and Gagne scored on a penalty shot at 10:17.
The Flyers recalled Scott Munroe from the Philadelphia Phantoms, their American Hockey League affiliate, to serve as Biron's backup in place of Antero Niittymaki who is out with the flu.