Briere scored all three Philadelphia goals, including the game-winner at 4:54 of overtime, to propel the Flyers to a 3-2 victory over Ottawa on Saturday.
The victory was the second straight for the Flyers and their third victory in their past four games. The loss snapped Ottawa's four-game winning streak.
"It was an inspiring effort by Danny," Flyers coach Peter Laviolette said.
"He was skating and in the battles and got knocked around. He was taking some and giving some. He has to be willing to take that from some big guys. You watch a guy like that, and I know it was a couple of skill guys, but Danny is not a big guy, he's a flyweight. But he gave our guys a lift, and he had a monster game."
Briere's fifth career hat trick came after a little push to the head by Ottawa's Kyle Turris that stirred a fight late in the second period.
The unlikely agitator was Briere, who last fought Nov. 20, 2009.
"It was a cheap shot on (Turris') part, he came down with a crosscheck to the back of my head when I was in a vulnerable position on the ice, he scraped my face on the ice and there was a lot of frustration there," Briere said.
"After that, I took the adrenaline and used it. I didn't think I got a fair shot and I felt I had to do something about it."
Turris and Briere had been jousting.
"It was a back-and-forth play, he gave me a shot, I gave him a shot back, we went in the box," Turris said.
"When we got out he gave me a shot, he asked me to go, during the faceoff we were talking back and forth and decided to go."
Briere now has 13 goals this season.
"I had the feeling they were going to play casual, with less than 15 seconds left in the period and knew I didn't have a lot of room," Briere said.
"I was just trying to jam the puck in there and get something going and lucky to find the puck."
Ilya Bryzgalov finished with 35 saves for the Flyers. Ottawa's Craig Anderson had 36 saves.
The teams traded goals in the third period. Briere scored at 9:12 of the period on a deflection off Ottawa defenceman Chris Phillips' stick, tying the game at 2-2.
Ottawa's Bobby Butler had given the Senators a 2-1 lead, poking in a rebound at 6:43.
Ottawa tied the game at 1-1 on a tap-in by Milan Michalek at 11:05 of the second period on the power play. The goal was Michalek's 20th of the season.
The point earned for the overtime loss keeps the Senators in the tight Eastern Conference playoff mix with 48 points. Ottawa is 7-1-2 in its last 10 games.
The Senators get another chance at Philadelphia in the home-and-home series Sunday night in Ottawa.
"It was a great game (tonight), I don't like the way we started, but for 50 minutes of the game, we played well enough to have the lead and in overtime that stuff happens," Senators coach Paul MacLean said.
"I thought we have grown as a team every day and tonight showed we can play (since the first game with the Flyers), we had a real legit chance to win the game."
Notes: Philadelphia's Scott Hartnell played in his 800th career game. Hartnell had his seven-game point streak snapped. Philadelphia's Claude Giroux also had his four-game points streak broken.