It was the final game of the regular season for both teams.
Drake Batherson, Warren Foegele and Dylan Cozens scored for the Senators (44-27-11), who went 6-1-1 in their final eight games. Claude Giroux had two assists.
Ottawa, who will face the Carolina Hurricanes in the Eastern Conference First Round of the Stanley Cup Playoffs, rested several veteran players for the second game in a row, including forwards Brady Tkachuk, Tim Stutzle and Michael Amadio, as well as defensemen Thomas Chabot and Jake Sanderson.
William Nylander scored the lone goal for the Maple Leafs (32-26-14), who lost seven straight (0-6-1) to close out the regular season. Dennis Hildeby made 35 saves.
Toronto has already been eliminated from playoff contention.
Batherson gave the Senators a 1-0 lead with a power-play goal at 6:04 of the first period. Giroux fed a pass from the right face-off circle to Batherson in front, where he redirected the puck to the short side past Hildeby.
Foegele made it 2-0 at 18:32 of the second period while on a power play, burying a long-distance snap shot low to the glove side.
Ottawa outshot Toronto 26-12 over the first two periods.
Nylander cut the deficit to 2-1 at 8:11 of the third period. Jacob Quillan carried the puck into the offensive zone and forced Reimer out of position before his centering pass deflected off the stick of Senators defenseman Cameron Crotty in front. The puck then bounced to Nylander, who backhanded it off Reimer's blocker into the net for his 30th goal of the season.
Cozens scored an empty-net goal at 19:54 to secure the 3-1 final.
