The former 3rd Rock from the Sun star will play Vincent, a celebrity impersonator who often poses as French Stewart, according to TV Line.
After becoming addicted to re-enacting movie scenes with celebrity lookalikes, Abed (Danny Pudi) finds himself in debt to Vincent.
The Greendale study group is then forced to impersonate celebrities as part of a scheme to earn Abed's money back.
Stewart played the alien Harry Solomon on 3rd Rock from the Sun between 1996 and 2001. His recent television credits include guest roles on Castle, Private Practice and Criminal Minds: Suspect Behaviour.