Giroux skated in slowly and faked the Panthers goaltender to the ice before roofing a backhander into the net during the tiebreaker's second round.
Sergei Bobrovsky made saves on Stephen Weiss and Mike Santorelli to preserve the victory for the Flyers, who entered the All-Star Game break in the Eastern Conference's fourth spot with a 29-14-5 record.
Philadelphia's Jakub Voracek and Brayden Schenn scored in regulation.
Florida goes into the break tied with Washington for first place in the Southeast Division.
2014: The Year in Fashion [PHOTOS]
LeBron James reveals his new Nike shoes