Ryan Spooner scored twice, the second with 39 seconds left in overtime, to give the Bruins rookies a 2-1 victory on Thursday night.
Michael Hutchinson stopped 33 shots for Boston.
Kevin Poulin made 31 saves, and Tony Romano scored for the Islanders.
Tyler Seguin, the No. 2 overall pick in this year's NHL draft, was scoreless. Seguin had a pair of assists, and Jordan Caron had a hat trick in Boston's 5-2 win on Wednesday.