Russell was activated from the 7-day concussion list prior to Thursday's game against the Cardinals, Jordan Bastian of MLB.com reports.
Russell wasn't expected to be back until Friday, but the Cubs made a last-minute decision to bring him back from the concussion list minutes before Thursday's matchup. He'll be available off the bench and could have a hard time finding playing time moving forward with how well Nico Hoerner has been playing of late.