Brooks Laich scored a shorthanded, unassisted goal at 10:07 of the first period, his 14th goal of the season, to put the Capitals ahead 1-0. Mathieu Perreault made it 2-0 when he scored his 12th goal of the season, with assists from Alexander Semin and Dennis Wideman, 42 seconds into the third period.
The Capitals have won three straight. They lead Winnipeg and Buffalo by four points for the eighth and final playoff berth in the Eastern Conference, and trail first-place Carolina by one point in the Southeast Division.
Jonas Gustavsson finished with 21 saves for the Maple Leafs, who lost their fourth straight and their 14th out of 16 overall -- and were shut out for a second straight day. Philadelphia beat Toronto 1-0 Saturday.