The 25-year-old forward, who was a restricted free agent, had filed for salary arbitration on July 5.
He had NHL career highs with 26 goals and 67 points in 81 regular-season games last season and had six points (two goals, four assists) in 10 Stanley Cup Playoff games.
"I think we went back and forth on a couple different ideas for term, and I think four years just kind of seemed like a good sweet spot for what both sides wanted to get out of it. Very excited that that's what we could do," Zegras said on Tuesday.
"I don't think anybody wants to go to arbitration, so it was really nice that we were able to get something done before then."
After the Flyers were eliminated in the second round of the playoffs by the Carolina Hurricanes, Zegras said he was hoping to get a new deal done with the Flyers.
Briere said he saw that attitude come out during contract negotiations.
"Trevor wanted to be here," Briere said. "He pushed on his side with his agent to move things along and to get the thing done. ... We're ecstatic that he wanted to stay here and was willing to sign a long-term deal to stay in Philly."
Selected by the Anaheim Ducks in the first round (No. 9) of the 2019 NHL Draft, Zegras has 253 points (93 goals, 160 assists) in 349 regular-season games for the Ducks and Flyers.
"I think I just had a lot of fun being at the rink and being around the guys," Zegras said when asked why Philadelphia was the right spot for him. "I find it lucky to be surrounded by so many amazing people, from the guys to the coaching staff to Danny and (Keith Jones, president of hockey operations), Dan Hilferty, the owner. I found that it was just a very good situation for me mentally, and it was a lot of fun on the ice, too."
Zegras was traded to the Flyers by the Ducks for Ryan Poehling, a second-round pick in the 2025 NHL Draft and a fourth-round pick in the 2026 NHL Draft on June 23, 2025.
"I'm really excited about him and how he's grown as an individual in the last year, especially, with us," Briere said. "But I think it goes ways way back. He's gone through a lot in his career, some ups and downs that weren't always easy. I think that makes you stronger in the long run. We're fortunate that we're the team benefiting from that."
NHL.com deputy managing editor Adam Kimelman contributed to this report
