Michel Ouellet and Gary Roberts scored power-play goals for the Penguins (46-24-11), and Marc-Andre Fleury stopped 34 shots. Jason Spezza and Dany Heatley scored for the Senators (47-25-9) in front of 20,064 at Scotiabank Place. Ray Emery faced 27 shots.
The Penguins moved into a fourth-place tie with Ottawa in the Eastern Conference. Both teams have 103 points with one game left.
Spezza opened the scoring midway through the first with a power-play goal as he scored on his own rebound.
Just over a minute later, Colby Armstrong knocked Emery into the net creating a scrum between both teams.
Things continued to escalate after Jarkko Ruutu charged Spezza, who retaliated by elbowing Ruutu in the mouth. Spezza was assessed two minutes for roughing and a five-minute major for elbowing.
The Penguins scored twice on the ensuing power play to take a 2-1 lead. Michel Ouellet tied the game at the 14-minute mark and Roberts gave the Penguins the lead as he beat Emery stick-side one minute later.
Senators tied the game on a two-man advantage four minutes into the second period as Heatley picked up his 49th of the season.
Senators' defenceman Tom Preissing did not play in the third period due to soreness in the groin. He will be re-evaluated Friday.
The Senators finished the regular season with a 1-1-2 record against the Penguins.
Notes: Ottawa RW Patrick Eaves missed his fourth straight game (lower body injury, day-to-day) D Lawrence Nycholat and RW Brian McGrattan were healthy scratchesaThe Penguins D Joel Kwiatkowski, D Alain Nasreddine, C Chris Thorburn, RW Georges Laraque and RW Nils Ekman were healthy scratches.