Matt Moulson added a goal and an assist for the Islanders, who had dropped 13 straight games on the Pens' home ice.
Pittsburgh goalie Marc-Andre Fleury was pulled from net after two periods as the Isles torched him for four goals on 17 shots.
Tomas Vokoun turned aside all seven shots he faced in the third.
Pascal Dupuis scored for Pittsburgh, which lost for the third time in four contests.
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