The win pulled the Leafs (81 points) within one point of the Bruins (82 points) for third place in the Atlantic division.
Toronto, holding the final wild-card position in the Eastern Conference, also has a game in hand.
Morgan Rielly, William Nylander and Nazem Kadri also scored for the Leafs, who swept the season series with Boston. Frederik Andersen was sharp with 32 saves, James van Riemsdyk added two assists.
David Backes and Dominic Moore scored for the Bruins, Tuukka Rask allowed two goals on 27 shots.
The Bruins fall to 38-28-6 on the year and will take on the Ottawa Senators in Boston on Tuesday.
Toronto improves to 33-23-15 on the year and will move on to face the Columbus Blue Jackets on Wednesday at home.
The Blue Jackets sit at second place in the Eastern Conference with 100 points and look to close the gap with first-place Washington.
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