Giroux beat Scott Clemmensen on the stick side to give the Flyers their first shootout victory in four tries this season.
Brayden Schenn and Jakub Voracek scored in regulation for the Flyers, while Sergei Bobrovsky made 23 saves. Bobrovsky also stopped three attempts in the shootout, after going 0 for 5 previously this season.
Mikael Samuelsson and Tomas Fleischmann had goals for Florida, and Clemmensen made 35 saves.
The injury-depleted Flyers started eight rookies.
The Panthers tied it 2-all on Fleischmann's goal in the second. Kris Versteeg grabbed the puck as it rebounded off the side boards. He skated in on Bobrovsky, then passed from the side of the crease back to Fleischmann in front, who wristed it in at 15:40.
The Flyers took a 2-1 lead on Voracek's goal at 17:59 of the first. Tom Sestito grabbed the puck in the right circle and his pass to Voracek was tipped in between Clemmensen's pad and the post.
The Panthers took a 1-0 lead during a power play 2:49 in. A shot by Stephen Weiss was blocked. The puck came out to Brian Campbell in the left circle, who passed across to Samuelsson above the right circle. His slap shot beat Bobrovsky on the stick side.
The Flyers tied it on Schenn's odd goal at 10:34, also during a power play. Schenn's shot hit Clemmensen's right skate and bounced up in the air, landing on his right shoulder. The puck trickled down his back and crossed the goal line just before a Flyers player dislodged the net. The goal was reviewed and the call on the ice was upheld.
Notes: Florida D Dmitry Kulikov is expected to miss six to eight weeks with a knee injury. The Panthers recalled D Tyson Strachan from San Antonio of the AHL. ... Flyers LW Scott Hartnell was named to the NHL All-Star roster. He will replace Chicago's Jonathan Toews, who bowed out because of injury. Hartnell has 25 goals and 19 assists, including five goals in his past two games.