Belfour made 25 saves to run his career record against Boston to 19-7-3. He has two wins against the Bruins this season.
Ville Peltonen, Stephen Weiss, Nathan Horton, Olli Jokinen and Martin Gelinas also scored for the Panthers, and Juraj Kolnik had three assists. Florida is 4-1-2 in its last seven games.
Florida has beaten Boston six straight times, including all four meetings this season by a combined 24-10 score. The Panthers also snapped the Bruins' four-game winning streak.
Marc Savard and Brad Boyes scored for Boston, which ended its road trip 4-2.
Boston's Hannu Toivonen replaced Tim Thomas before the second period. Thomas, who won at Tampa Bay on Friday night, allowed three first-period goals on 19 shots. Toivonen stopped 28 shots.
Goals by Peltonen, Weiss and Horton gave Florida a 3-0 first-period lead. Weiss scored on the power play, and Horton's goal was short-handed.
Horton scored at 19:11 of the first period, when he one-timed a pass from Weiss in the left circle. Horton has seven goals in his last nine games to run his season total to 22.
Weiss scored from in close during a five-on-three advantage to give the Panthers a 2-0 lead at 7:19. Jokinen's shot rebounded in front to Gelinas, who passed the puck to Weiss.
Boston made the most of a five-on-three power play midway through the second period, scoring twice within 48 seconds. Savard scored his 21st at 14:09 and Brad Boyes netted his 12th at 14:57 to pull the Bruins to 5-2.
Notes: Weiss and Gratton also had three-point nights. Jokinen's goal was his team-high 25th. ... Florida hasn't lost to Boston since Nov. 3, 2005. ... The Panthers improved to 10-2-3 in their last 15 home games. ... Boston was seeking its first five-game winning steak since a six-game run from Jan. 29-Feb. 10, 2004.