Jeff Carter scored a goal and set up Knuble's tally in the third period for the rebounding Flyers, who beat the Islanders 4-1 Saturday for their third straight win.
Carter staked the Flyers to a 1-0 lead in the first and then followed up his rebound on a short-handed break and caromed a shot in off Knuble at 9:31 of the third.
"I don't know," Knuble said when asked how the puck got past Rick DiPietro. "I turned out of the way and started to turn and head back. I felt it hit me and rattle off my stick. I just assumed it was behind the net or something."
Knuble then noticed shoulders droop on the Islanders bench and realized he had notched the NHL-high 13th short-handed goal against New York. Philadelphia is second in the league with 13 scored while killing penalties.
That kept Philadelphia rolling after an 0-8-2 skid. The Flyers snapped a team record-tying 16-game streak of scoring three goals or fewer.
"We lost 10 in a row and we just couldn't get those breaks," Knuble said. "Now pucks are hitting guys and going in."
Knuble started the play by blocking a shot from the point by Islanders forward Miroslav Satan.
"It seems like their penalty killers are jumping on the top guy, and that's happened a few times to us," Satan said.
Scottie Upshall added an empty-netter with 26.4 seconds left. Braydon Coburn also scored and Martin Biron made 33 saves in his third straight start. He didn't know immediately after the game if he would play Sunday when the Flyers finish their New York swing against the Rangers.
"We got the lead, gave them a little bit of life in the second, but really played extremely well down the stretch," Biron said.
Bill Guerin scored and DiPietro made 27 saves for the Islanders, 1-3 following a six-game winning streak.
DiPietro, whose grandmother died this week, left the team immediately after the game to attend the wake and won't play Sunday when the Islanders face Florida. He made his 14th straight start Saturday, dating to Feb. 2 (7-6-1).
The pace picked up in the second period when the teams traded power-play goals amid a flurry of 25 shots.
New York tied it with a rare man-advantage tally on its first of three chances. Guerin skated inside the right circle and zipped a drive over Biron's right shoulder at 8:30, giving the captain 20 goals in his first season with the Islanders. He is the second NHL player to score that many in a season for six teams.
"I don't know if it's good or bad," Guerin said. "Maybe it's a good level of consistency over the years. Part of my job is to score goals. It's my mind-set. I'm just fortunate to be able to play on some great teams with great players."
The Islanders, who have the league's worst home power-play percentage, had scored only once in their previous 28 chances anywhere the previous six games.
Coburn restored Philadelphia's one-goal lead with 5:36 left in the first, taking a pass in the right circle from Danny Briere - who faked a shot - and whistling a one-timer past DiPietro. The Flyers came in with the second-best power play overall, third on the road.
It was Philadelphia's only power play of the game.
"Our power play hasn't been up to where we want it," Briere said of the Flyers, who have scored on three of their past 13 chances. "My first thought was to take a shot. As I wound up, I saw out of the corner of my eye Braydon kind of open that lane."
Carter made it 1-0 when he got between a pair of Islanders defenders in front and quickly converted a pass from Upshall with 6:01 left in the first for his 21st goal.
