Claude Giroux had a goal and an assist to extend his point streak to nine games, and Tim Stutzle had two assists for the Senators (5-9-1), who have lost eight of nine (1-7-1). Cam Talbot made 31 saves.
"I thought we played well again," Ottawa captain Brady Tkachuk said. "We stuck to our game, we were getting behind them. That's a good, veteran, older team who knows how to play the right way for 60 minutes. I thought we did a good job of matching that."
Oliver Wahlstrom gave New York a 1-0 lead at 11:53 of the first period, scoring blocker side with a wrist shot from the top of the right circle on a power play.
The Islanders are 6-0-0 when scoring first this season.
"It's nice to score the first goal, that's for sure. We've had some comebacks, too," Lambert said. "But tonight, I thought we did a really good job with the lead, and it was, really, a character win. It was as much a character win, or more, as the comebacks. We fought through a lot of adversity tonight."