Chara, a 42-year-old defenseman, has an undisclosed injury. John Moore replaced him in the lineup.
The Bruins have a 3-0 series lead on the Carolina Hurricanes and are looking to complete the sweep Thursday.
“It’s a big loss, but hopefully he’ll be back soon,” longtime Bruins teammate David Krejci said in a pregame interview with NBC. “It’s an opportunity for other guys.”
Chara spoke to reporters on the Wednesday off-day and was seen in the arena on Thursday morning. He had been set to play in his 176th career playoff game, which would have tied him with current San Jose Sharks player Joe Thornton and Mike Modano for 40th all time in playoff games played.
Chara typically plays on the Bruins’ top pairing alongside Charlie McAvoy. In 16 playoff games this spring, Chara has averaged 22:32 a night, while scoring one goal and two assists.