The Senators punched their return ticket to the post-season with the help of Milan Michalek, who contributed a goal and two assists.
Ottawa will make a reappearance in the playoffs following a 13th-place finish last season.
Mark Streit scored and Al Montoya yielded five goals on 32 shots for the Islanders.
Pregnant Mila Kunis wins 'Best Villain' at MTV Movie Awards
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend