Braden Holtby, making a rare start for the Capitals, made 24 saves including a game-saving stop on Matt Moulson from point blank range during an Islanders power-play midway through the third period.
The Islanders were unable to capitalize on six power-play opportunities.
I forgot how many power-plays they had, I didn't think they had that many scoring opportunities, Holtby told reporters.
I think we did a great job of not letting them see anything from up top and that's how you're usually successful on power-plays. Every time they'd go to shoot, they'd see a guy in front of them and try to pass.
The Islanders moved the puck well and generated good pressure in the Capitals zone, but had just eight shots on goal during their periods with extra players on the ice.
I thought we had some good looks, Islanders coach Jack Capuano said.
We had great zone time, we had good looks. We were spreading them out. We had net presence a few times, but instead of getting pucks to the net, we were moving it down low and back up top, east, and west. We didn't seem to get the puck through.
Jason Chimera tipped in a perfect pass by Ovechkin less than four minutes into the game and Nicklas Backstrom scored his first goal in 22 games tapping in an Ovechkin rebound early in the second period.
Michael Grabner burst down the left wing beating John Carlson to a loose puck and beat Holtby with a backhand to draw the Islanders to within one later in the second period.