''It's a good feeling,'' Marner said. ''We've got to make sure we just keep going with the pedal down.''
William Nylander and Pierre Engvall also scored, and Jack Campbell made 21 saves. Toronto was 7-2-1 against the Canadiens in the season series as the Original Six rivals look poised to meet in the playoffs for the first time since 1979.
''We've come a long way,'' said Nylander, one of the few remaining players from the Leafs' last-place finish in 2015-16. ''It's been a long process and a lot of hard work. This is just a stepping stone for where we want to go.''
Toronto won its first division crown since 2000.
''It's unbelievable,'' said Toronto winger Wayne Simmonds, who signed with his hometown team in free agency. ''For me and for the team, this is a great accomplishment. It's only getting started.''
Nick Suzuki and Brett Kulak scored for Montreal, and Jake Allen stopped 23 shots.
Toronto beat Montreal 5-2 on Thursday night to open the two-game set.
Canadiens: At Edmonton on Monday and Wednesday nights.
Maple Leafs: At Ottawa on Wednesday night.
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