Reimer's 2nd straight shutout lift Leafs over Sens
Kessel and Bozak each had a goal and two assists, while Dion Phaneuf, Luke Schenn and Cody Franson also scored for Toronto. Reimer stopped 49 shots for his third shutout of the season and has now made 74 saves in his last two games.
Craig Anderson, making his 17th straight start and 50th appearance, had little help from his teammates as he faced 40 shots.
Ottawa fell to 3-2-0 against Toronto this year.
With their sixth straight loss, the Senators are on their longest losing streak since an 0-9-2 stretch last season.
Despite the loss, the Senators remain in seventh place in the Eastern Conference, but the Leafs are just one point back in eighth and Washington three points back in ninth. Both teams have games in hand on Ottawa.
The Senators have made a habit of rallying to win this season, but the hole was too deep as they entered the third period trailing 3-0.
Any hope quickly faded as Schenn made it 4-0 early in the period before Franson's power-play goal completely deflated Ottawa.
Playing their second game in as many nights, the Senators got into trouble early as the Leafs jumped out to a 2-0 lead in the first period.
Midway through the period, Kessel managed to pick up his own rebound and beat Anderson through the legs to open the scoring.
Toronto made it 2-0 late in the period with the man advantage as Kessel found an open Phaneuf, who beat Anderson with a quick wrister.
Ottawa could not find a way to beat Reimer and even outshot the Leafs 21-9 in the second.
Bozak gave the Leafs a commanding 3-0 lead with his ninth of the season as he broke in around the defense and lifted a backhander over a sprawled Anderson.
Notes: The Senators were without C Peter Regin (shoulder, out for season), C Jesse Winchester (concussion, indefinitely). D Brian Lee (lower-body injury, day-to-day). ... D Mike Komisarek, LW Darryl Boyce and LW Jay Rosehill were healthy scratches for Toronto.