Aleksander Barkov, Drew Shore and Nick Bjugstad each scored for Florida, which ended the Islanders' seven-game road winning streak.
Tim Thomas stopped 31-of-33 shots.
Thomas Vanek and Colin McDonald provided New York's offense.
Kevin Poulin gave up four scores on 26 shots as the Islanders fell on the road for the first time since Dec. 12.
Notable deaths of 2014 [PHOTOS]
Michael Sam cut from the Dallas Cowboys