The show has also extended its booking period at the Theatre Royal Drury Lane until 31 March 2013, releasing 389,000 for sale.
Stenson - who is best known for her long-running part on Channel 4 soap Hollyoaks and made her West End stage debut as Margot in Legally Blonde - will join the Theatre Royal, Drury Lane production on 23 May 2012.
Carley Stenson's other stage credits include Grease (Palace Theatre, Manchester), Summer Song (BridgeWater Hall), Remembering Diana (Her Majesty’s), Godspell (Globe Theatre, Blackpool) and Aida (Opera House, Manchester).
As previously reported, Legally Blonde will shutter in the West End on Saturday 7 April 2012. The Olivier and Whatsonstage.com Award-winning screen-to-stage musical opened in December 2009 at the Savoy Theatre. The show continues its UK tour.
A former member of girl band Girls Aloud, Kimberly Walsh will play her final performance as Princess Fiona on 21 May 2012. Walsh took over from Amanda Holden who originated the role in the West End, on 5 October 2011.
Stenson will join the new West End company, lead by Dean Chisnall and Neil McDermott as Shrek and Lord Farquaad. Richard Blackwood takes the role of Donkey which he has played since the show opened on 14 June 2011 (previews from 6 May).
Shrek the Musical premiered in December 2008 on Broadway, where it ran for just over a year, a revised production subsequently touring America.
The New York production was nominated for eight Tony Awards, Tim Hatley winning for Best Costume Design of a Musical. The show's West End offering is based on the revamped US touring production, which launched from Chicago in July 2010. That production continues to tour, having visited 60 US cities.
The show's Anglo-American creative team is led by directors Jason Moore and Rob Ashford and includes David Lindsay-Abaire (book and lyrics), Jeanine Tesori (music), Tim Hatley (scenic, costume and puppet design), Hugh Vanstone (lighting design), Peter Hylenski (sound design), and Josh Prince (choreography).
Shrek is produced by Neal Street Productions and, in the company’s theatrical debut, the Hollywood studio Dreamworks Animations.
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