Blues general manager Doug Armstrong said Oshie had surgery Thursday to repair the ankle.
"He's out a minimum of three months at which point he'll be re-evaluated," Armstrong told ESPN.com.
The injury occurred when Columbus' Samuel Pahlsson fell on Oshie during a scrap with 11 minutes to play.
Oshie was helped off the ice in the third period, and he was wearing a support boot on it in the dressing room.
A first-round pick of the Blues in 2005, Oshie has a goal and nine assists in his second season with the team.
The club recalled forwards Nick Drazenovic and Chris Porter from AHL Peoria.
Information from The Associated Press was used in this report.