Bergeron scored on a rebound off Brad Boyes' drive from the point, putting the puck past helpless goalie Jean-Sebastien Aubin. Bergeron was the star on consecutive nights. He scored the lone shootout goal in the Bruins' 3-2 victory at Washington on Wednesday.
The Bruins hadn't won three straight since Jan. 23-26.
Bryan McCabe got Toronto even at 1-1 on the power play when his slap shot went between goalie Tim Thomas' legs with 6:42 remaining in regulation.
Thomas made 24 saves for the Bruins (7-7-2), who have earned all their victories this season in one-goal games.
Phil Kessel scored a power-play goal giving the Bruins a 1-0 lead when he knocked a rebound past Aubin at 14:09 of the first period.
Kessel, the No. 5 pick in this year's NHL draft, scored in back-to-back games for the second time this season. He is second on the team with five goals.
Aubin made 34 saves for the Maple Leafs, who had a four-game winning streak snapped.
Boston has been mired near the bottom of the Eastern Conference all season, but moved out of last place in the Northeast Division by passing idle Ottawa.
The Maple Leafs lost for the second time in eight games and failed to score at least four goals for the first time in five contests.
Toronto's Tomas Kaberle, who entered as the scoring leader among NHL defencemen, had an eight-game point streak snapped.
Notes: McCabe tied Kaberle with his 17th point. ... This was the second of five meetings between the teams in a 28-day stretch. Toronto won the earlier matchup 6-4. ... G Andrew Raycroft missed his second straight game for Toronto with a groin injury. ... Toronto fell to 6-3-1 on the road.