Captain John Tavares collected two goals and two assists as the New York Islanders came from behind and ended the Bruins eight-game home winning streak at the TD Garden.
Frans Nielsen scored twice and Kyle Okposo tallied and set up two others.
Patrice Bergeron and Daniel Paille tallied 25 seconds apart in the second period for the Bruins, who lost in regulation for the first time at the Garden since a 4-3 setback to New Jersey on Oct. 26 (13-1-2).
New York scored a pair of late goals in the second period to forge a 3-3 tie.
A pair of quick strikes had given the Bruins a 3-1 lead, but Nielsen trimmed the deficit by cleaning up a loose puck and Okposo knotted it up after his shot deflected off the skate of Bruins left wing Brad Marchand with three seconds left in the second.
BRUINS NOTEBOOK: Krejci has collected three goals and three assists on his overall point streak and five and seven, respectively, on his home stretch. ... Bergeron's one-timer from the inner edge of the right circle gave Boston a 2-1 lead with 7:27 remaining in the second period before Paille deflected Zdeno Chara's bid from the left point shortly thereafter. ... New York nearly forged a 1-1 tie with 4:35 remaining in the first period, but RW Cal Clutterbuck's bid was denied after officials lost sight of the puck and whistled the play dead.