The rookie disclocated his right shoulder during a fight last Thursday night.
"He's going to have surgery in early January and he's done for the year," Jackets general manager Scott Howson told ESPN.com Monday.
"He's four to six months out in terms of return to play -- closer to six months. So he's not going to return this year."
Brassard was tied for the NHL rookie scoring lead with 25 points (10-15) in 31 games and was among the candidates for the Calder Trophy as rookie of the year.
It's a huge blow to a Jackets team that wasn't that deep at center to begin with.
Brassard was the sixth overall pick in the 2006 draft and was the NHL's rookie of the month for October. He has earned points in 20 games this season.
Pierre LeBrun covers the NHL for ESPN.com. Information from The Associated Press was used in this report.