The deal has a base salary of $2 million with $1.75 million in performance incentives, the team said.
The deal keeps the 42-year-old Slovak native with the team through next season.
Currently playing in his 21st season, Chara ranks sixth in franchise history in games played (948).
Chara was drafted in the third round by the Islanders in 1997 and signed with Boston as a free agent in 2006 after playing with the Senators.
Chara won the Norris Trophy as the league's top defenseman for the 2008-09 season and has been in six All-Star Games.
He has 199 career goals with 440 assists and won a Stanley Cup with Boston in 2011.
Also for the Bruins, center Sean Kuraly sustained a broken right hand in Thursday's game against the Devils, the team said Saturday.
The 26-year-old had surgery and is expected to recover in about four weeks.
Kuraly has eight goals and 13 assists this season.