Phil Kessel tallied twice and added one assist, 3, at Air Canada Centre.
James Reimer, who blanked Pittsburgh and Ottawa in consecutive starts, stopped 27-of-30 shots for the win.
"There's not a whole lot of scoreboard watching on our part," said Leafs head coach Ron Wilson about his club, which vaulted over the idle Sens into seventh place in the East. We just try to take care of our own business and worry about ourselves."
Jordan Eberle scored a pair of goals and Jeff Petry picked up a goal and one helper for the Oilers, whose three-game win streak was halted.
Devan Dubnyk allowed five goals on 29 shots for the loss.
Kessel began the second-period's offensive fireworks by giving Toronto a 3-2 advantage at 1:45, slipping a Matthew Lombardi pass home from the left post. Bozak stole the puck from an Oilers defender in the slot and chipped it over Dubnyk to make it 4-2 at 4:15.
Petry then brought the Oilers within 4-3 at 13:24 on a shot from the blue line, but Lupul kept the offense flowing for the hosts by tapping in a Dion Phaneuf rebound at 16:54.
Kessel iced the game thanks to an empty-netter with 1:05 remaining.
"We turned a lot of pucks over and gave them a ton of chances," lamented Eberle. "When you give them all that, they'll put pucks in the net eventually no matter how well your goaltender plays."
Any hopes of Reimer turning in his third shutout in succession were dashed just 21 seconds after the opening faceoff, as Eberle capitalized off a turnover and scored from the right side of the crease.
But MacArthur converted off a turnover in the slot at 8:21 to tie the game, and Gardiner put the Leafs ahead at 13:45 by converting a Mikhail Grabovski dish, before Eberle struck again off a give-and-go with Petry at 17:30.
Toronto has won four of its last six home games over Edmonton...Kessel notched his second straight three-point game, after a goal and two assists in a 5-0 win at Ottawa on Saturday night...Grabovski and Phaneuf each collected two assists...Oilers head coach Tom Renney was not behind the bench, after suffering a head injury that required a dozen stitches during a Monday practice session. Associate head coach Ralph Krueger took the reins.