Gustavsson, making his first start in 16 days after a surgical procedure for an abnormal heart rate, made 25 saves to help the Leafs, the Northeast division's bottom team, hand the Bruins their fourth consecutive loss.
"It's pretty big for me, the first shutout, but in the end we won and that's what counts," Gustavsson, who received a standing ovation after the game, told reporters.
"I can't say if it (the heart rate) will be fine all the time, but I feel fine and it's important that we got the win."
"It wasn't what I was expecting," the 24-year-old said of his two surgeries. "But you have to stay positive and make the most of those situations."
"It was a huge boost for us -- he played well and deserved the shutout," said Kaberle, who scored Toronto's first goal 2:24 into the second period.
Blake's goal, his seventh of the season, came in the third.
Boston netminder Tuukka Rask, who had beaten Toronto twice, wound up with 29 saves.
Toronto peppered Rask with 16 shots in the third while division rivals Boston had only five.
(Reporting by Gene Cherry in Salvo, North Carolina. Editing by Peter Rutherford and Julian Linden)