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.
Exploding whale video goes viral on Internet
Benedict Cumberbatch's dramatic reading of R. Kelly lyrics is just what you need