The Mad Men actor will star in the CBS drama's seventh season as a US senator, according to TV Line.
The premiere will take place four months after the show's sixth season finale, and will see Moses's character investigating the BAU team following a botched mission.
The episode will also see Emily Prentiss (Paget Brewster) return to the show, after faking her death last season.
Mark Moses has played Paul Young on Desperate Housewives since 2004 and also played 'Duck' Phillips on Mad Men. His other television credits include guest roles on Human Target, CSI: Miami and Castle.
Criminal Minds showrunner Erica Messer recently revealed that the seventh season will focus on the relationship between Hotch (Thomas Gibson) and JJ (AJ Cook), and that the BAU team will face a financial crisis that threatens to dismantle their operation.
Criminal Minds will return to CBS on Wednesday, September 21 at 9/8c.
> Thomas Gibson signs new Criminal Minds deal
Watch a scene from Criminal Minds' sixth season finale below: