Boston took a 2-1 lead at 6:29 when Chara scored his ninth goal of the season. Bernier stopped Krejci's shot from the high slot, but the rebound came to Chara in front of the net and scored on a backhand shot.
Bernier finished with 30 saves.
Chara, Boston's captain, was relieved to see the Bruins put the losing streak behind them.
"We played better, it's as simple as that," Chara said. "You can't really pick one thing than we did better than all those games. Overall, I thought we were better. We were tighter defensively, better offensively, stronger on pucks, more physical. I thought we had a good, strong 60-minute game."
In winning their three previous games and five of their past six, the Maple Leafs had worn down opponents with their speed. The Bruins were able to slow them down.
"We talked about their speed and their energy," Julien said. "They have a lot of guys who are trying to make a real good impression. When you are young and energetic you come real hard and we talked about doing a good job, especially in the neutral zone where they move the puck around well."