Fiddler then knotted the score with a backhander past Bruins goaltender Tuukka Rask.
After a scoreless overtime, the contest went to a shootout. After Boston's Patrice Bergeron scored in the first round, Seguin tied it in the second with a forehand shot.
Following a miss by the Bruins' David Krejci, Peverley secured the win with a shot that went between Rask's legs.
Torey Krug and Milan Lucic each scored and Rask finished with 34 saves for Boston, which fell for the fourth time in five games.