Artturi Lehkonen scored twice for the Canadiens (13-33-7), who are on their longest winning streak of the season. They are 5-3-0 in eight games since Martin St. Louis replaced Dominique Ducharme as coach Feb. 9.
"I feel like we've gotten better and better and better and we're doing it consistently now," St. Louis said. "We come to work, take care of the team, play the game the right way. You're going to be in a lot of games. You don't know if you're going to score all the goals or get all the saves, but at the end of the day, you've given yourself a really good chance to win if you've played that way."
Colin White scored in his season debut for the Senators (19-27-5). The forward had shoulder surgery after a collision with Toronto Maple Leafs forward David Kampf during a preseason game and missed the first 50 games of the regular season.
"I think I said it a few weeks back, but seeing it from the outside, you see how lucky we are to play hockey and play the game we love," White said. "To be back out there with the guys and go through the emotions through the game and after the game and win or lose as a team, we're all in it together, and just to be with them again, it's great for me."
Matt Murray made 30 saves for Ottawa, which played without defensemen Thomas Chabot and Nikita Zaitsev due to non-COVID-19 related illness.
"We didn't have the puck in their zone enough to give our [defensemen] a breather," Senators coach D.J. Smith said. "We had bad pinches and some [players] not covering guys. And ultimately, you're missing [Chabot] with those power plays. There were a lot of things that were good, but offensively we just weren't very good."