Marc-Andre Fleury made 21 saves to pick up his third shutout of the season and the 14th of his career.
The Penguins, defending Eastern Conference champions, began the night four points out of a playoff position.
Pittsburgh played without captain Sidney Crosby, who is listed as day-to-day after suffering a groin injury Sunday in a loss to Washington. The Penguins won at home for the sixth time in seven games.
Yann Danis made 27 saves on 28 shots, but the Islanders lost for the eighth time in 10 outings. New York has won just once in its last 21 road games.