Frans Nielsen and Kyle Okposo each scored in the shootout to give the Islanders a 2-1 win over the Blues at the Barclays Center.
Mikhail Grabovski scored in the third period for New York to tie the game at one.
Thomas Greiss stopped 31-of-32 shots to earn the win for the Islanders, who won their fourth straight game.
Kevin Shattenkirk tallied the lone goal for St. Louis, which has lost three of its last four games. Brian Elliott made 24 saves in the loss.