Ottawa (11-20-2) had goals from Josh Norris (2), Drake Batherson and Tim Stützle while Anton Forsberg made five saves before he was replaced by Filip Gustavsson who turned away 23 shots. Mike Matheson (2), Dominik Simon, Evgeni Malkin, Sidney Crosby and Jake Guentzel scored for the Penguins (24-10-5) while Tristan Jarry stopped 39 shots.
"We stayed on it all night," Sens head coach D.J. Smith said. "We've won plenty of games this year where we didn't play like that."
Trailing 5-1 after 40 minutes, the Senators attempted to mount a serious comeback in the third.
Stützle got one back for Ottawa 1:45 into the final frame as he deposited a rebound past Jarry after the Pens netminder had initially stopped Zach Sanford. Norris' 17th at 3:34 cut the deficit to 5-3 as Batherson's pass hit his skate and went in at the top of the crease.
After Formenton was stopped by Jarry on a penalty shot at 7:27, Norris would score again less than a minute later at 8:02 as he had his stick on the ice to steer Erik Brannstrom's gorgeous backhand pass home for his 18th of the year, a new career high.
"We knew we shouldn't be down by four at that point," Smith said. "I thought we did a lot of good things. We had the puck, we broke out well … we had a lot of scoring chances."
Guentzel scored into the empty-net with 46.6 seconds left.
"In the third, we just tried to stick to what we were doing and I think we've got to take some pride in that as a group," Thomas Chabot said. "We stuck to our game plan."
It was a frantic first period that saw the teams combine for four goals. Simon gave the hosts a 1-0 lead at 4:28 as he found a loose puck in Nick Holden's skates and beat Forsberg high for his second goal of the season.
Batherson tied the game at 10:12 as he potted his own rebound high after Jarry had stopped his initial shot on a partial breakaway as the Senators All-Star scored his 12th of the year.
Pittsburgh had a 2-1 lead at 11:40 as Malkin grabbed a loose puck out front off of Kasperi Kapanen's shot to bury his third of the campaign. The Russian thought he had his second of the night at 13:41 as his shot from the goal line on the power play hit Forsberg's stick and went in but after D.J. Smith challenged, the goal was waved off due to the entry being offside.
Despite the goal being overturned, it spelled the end of the night for Forsberg who was replaced by Gustavsson as he made his first appearance against the team that drafted him. The Penguins extended its lead at 15:59 as Matheson poked in a puck out front after Gustavsson couldn't cover Brock McGinn's effort in a period in which the Sens tallied 22 shots on goal.
"We played well [in the first]," Smith said. "[But] it's not always going to go your way. Just stay with what you do and I thought we did that again in the second period."
Crosby's seventh of the year at 11:32 of the second made it 4-1 as he scored on a backhander on the power play from in-close before Matheson's second of the game at 18:41 pushed the Pens lead to four as he used Josh Brown as a screen to beat Gustavsson from the top of the left dot.
"There's a lot of things to be happy about with our game," Brady Tkachuk said. "Nobody likes losing but we put up a fight right to the very end. We can definitely take a lot of positives from tonight's game.
Sens forward Nicholas Paul played in his 200th career NHL game.
Ottawa is back in action Saturday as they continue their road trip when they visit Washington.
