Travis Hamonic and John Tavares each had a goal and an assist in the third period and defeated the Senators 5-2 on Friday night.
Hamonic beat Andrew Hammond with a slap shot at 2:58 of the third to give New York a 3-2 lead and Tavares slipped a backhand past Hammond at 7:03 for some insurance.
Kyle Okposo scored on a bank shot off the backside of Ottawa defenseman Jared Cowen to finish the scoring.
Nick Leddy and Cal Clutterbuck also scored for the Islanders while Jaroslav Halak made 28 saves for the win.
Bobby Ryan and Erik Karlsson had goals for the Senators, who were coming off a five-game, 12-day road trip. Hammond had 29 saves.