Giroux's score on a quick wrist while skating through the left circle gave the Flyers a 3-1 edge, which they needed after Buffalo's Jochen Hecht came up with a shorthanded tally in the final frame.
Max Talbot and Simon Gagne also scored for Philadelphia, which snapped a three-game losing streak.
Ilya Bryzgalov tuned aside 18-of-20 shots for the Flyers.
Brian Flynn scored and Ryan Miller made 25 saves for the Sabres, who fell for the fourth consecutive time.
Celebrity Families of 2014 [PHOTOS]