"I'm excited to be back, obviously," Thornton told the Boston Globe at the team's morning skate. "It was a tough night to sleep for other reasons this time, which is good. I was a little excited. It's been a long time."
Thornton served a 15-game suspension for attacking the Pittsburgh Penguins' Brooks Orpik in a game Dec. 7. Eriksson suffered a concussion earlier in that game when he was hit by Orpik. Both Thornton and Eriksson have been sidelined since.
"It's been a long time, it feels like," Eriksson told the Globe. "So it's going to be nice to be back."
Along with activating Eriksson from injured reserve, the Bruins assigned Justin Florek to Providence of the American Hockey League.
The Associated Press contributed to this report.