Thorpe, who previously played the role at the Apollo Victoria for two years from April 2008, replaces Louise Plowright who has withdrawn from the production due to ill health.
Thorpe recently revisited another role in the West End - Frauline Kost in Rufus Norris' production of Cabaret at the Savoy Theatre, having previously played the part at the Lyric Theatre in 2006.
Her other recent credits include Crazy For You at the Open Air Theatre, Regent's Park and at the Novello Theatre (for which she was nominated for a Whatsonstage.com Award) and Mamma Mia! at the Prince of Wales.
Wicked, which recently celebrated its five millionth theatregoer in the West End, currently stars Louise Dearman (Elphaba), Gina Beck (Glinda), Ben Freeman (Fiyero), Keith Bartlett (The Wizard), Christopher Howell (Doctor Dillamond), Sam Lupton (Boq), Katie Rowley Jones (Nessarose), Hayley Gallivan (Standby Elphaba) and Lucy van Gasse (Standby Glinda).
Regarding Plowright's illness, a statement from the producers today said, "the entire company wish her a full and speedy recovery".
Thorpe will play the role until new cast changes are implemented on 16 November 2013.