Tim Stutzle had a goal and an assist, and Dylan Cozens scored his 100th career NHL goal for the Senators (26-21-7), who have won three straight games.
Linus Ullmark made 26 saves in his first start for the Senators since taking a leave of absence on Dec. 28.
Timo Meier scored, and Jake Allen made 30 saves for the Devils (28–25-2), who have lost three of their past four games.
After killing back-to-back penalties to start the first period, the Senators got on the board first on a power play of their own.
Tkachuk wristed a pass at the left circle from Drake Batherson and beat Allen glove side to give the Senators a 1-0 lead at 13:38 and break New Jersey’s streak of 17 straight successful penalty kills.
It was the first time the Senators had scored on the power play in six games.
The Devils tied it 1-1 at 18:16. Cody Glass fought through a netfront battle and backhanded the puck from behind the net while falling to Meier, who one-timed it from the right circle past Ullmark.
Dougie Hamilton earned the secondary assist on Meier’s tying goal, extending his point streak to 11 games (12 points; two goals, 10 assists).
The Senators regained the lead 2-1 just 37 seconds into the third period. A Tkachuk shot off the blocker of Allen rebounded to Cozens, who won a netfront battle for the puck and pushed it past Allen.
Connor Brown appeared to score the tying goal for New Jersey at 16:00 of the third period on the power play, but it was ruled a hand pass after review. Brown closed the puck with his hand off a rebound and attempted to drop it to his stick near the left post, but it was deflected straight off Ullmark’s and into the net.
Stutzle put the Senators up 3-1 at 17:53, capitalizing on a 2-on-1 opportunity.
Shane Pinto scored into an empty net to make it 4-1 for the Senators at 18:41.
Ottawa defenseman Thomas Chabot left the game in the third period and did not return.
