Bergeron, 27, is linked to the Bruins through the 2021-22 season.
The agreement is worth $52 million.
"Really happy to be a Bruin, hopefully for life," Bergeron said at a Friday news conference. "I will hopefully retire a Bruin. That's the goal, that's what I want."
Boston made Bergeron the 45th overall selection in the 2003 draft and he played his first NHL game that season. He's appeared in 579 NHL games -- all with the Bruins -- scoring 153 goals and assisting on 280 others.
He had a plus-60 rating over the last two years in face offs, a statistic that leads the NHL over that time.
Bergeron was a member of the Boston team that won the Stanley Cup in 2011 and lost in Game 6 of the finals to Chicago this year.
The Bruins announced this week goaltender Tuukka Rask signed an eight-year, $56 million contract.