Eaton scored 2:35 into overtime in his 600th NHL game to give the Islanders a 2-1 win over the Ottawa Senators on Friday night.
The 34-year-old defenseman took a pass from Milan Jurcina and put the puck into an open right side for his 24th NHL goal -- his first since Nov. 28, 2009.
"The circumstance is the big thing. We're just trying to get points and keep climbing up the standings," Eaton said. "Every point's big and for it to be an OT winner makes it a little more memorable."
The Islanders tied Tampa Bay for 11th in the Eastern Conference with 49 points, nine points behind eighth-place Toronto, which plays in Ottawa on Saturday night.
"We play Buffalo at home [Saturday] and we're a confident bunch right now," said P.A. Parenteau, who assisted on both goals. "We play with a lot of passion and we know what's at stake in the next two weeks. Nothing's impossible for us."
John Tavares, chosen the NHL's first star of the month on Wednesday, failed to record a point for the second time in four games following a 12-game points streak. The Islanders' first overall pick in the 2009 draft had nine goals and 13 assists for 22 points in 13 games in January, including four in a 5-2 win at Carolina on Tuesday.
"Obviously it was a pretty tight hockey game and a big game for both teams," Tavares said. "We came back, down by a goal, and it was nice to see a guy like Mark Eaton -- who has done a lot of great things for us this year, the little things that don't get a lot of the press -- score, and it's a nice win for us."
Zack Smith scored a short-handed goal late in the second for the Senators, who have lost five in a row, the last four in regulation.
Ottawa's Craig Anderson stopped 30 shots in his 16th straight start.
"Their play without the puck in the neutral zone was better than ours," Senators coach Paul MacLean said.
Smith scored with 12.6 seconds left in the second. The Ottawa center carried the puck out of his zone and raced down the ice before taking a wrist shot from the top of the left faceoff circle. Nabokov got his glove on the shot but the puck carried on and flew behind him into the net.
Martin tied it 5:27 into the third. Parenteau drew Senators defensemen Sergei Gonchar and Jared Cowen to the left side before feeding a pass to the right side of the slot, where Martin was left unguarded to fire a wrist shot past Anderson for his sixth goal.
Parenteau's assist on Eaton's goal extended his career high to 36. He had 34 assists last season, and 33 in 2009-10.
Jurcina went to the dressing room 8:16 into the third after he was attended to on the ice by a trainer. Jurcina, who landed on his backside following a hit by former teammate Zenon Konopka behind the New York net, quickly returned.
The game was delayed with 9.7 seconds remaining in regulation because of a broken curved glass panel at the far end of the Senators' bench.
- Former Islanders stars Denis Potvin and Billy Smith were introduced to the crowd and shown on the video scoreboard during the game. Potvin is an analyst on Senators TV broadcasts and Smith watched from the stands.
- The Senators' five-game homestand is their longest of the season.
- C Jim O'Brien made his season debut for Ottawa after he was recalled from AHL Binghamton earlier in the day. RW Bobby Butler was left out of the lineup.