The Hollyoaks actress will replace Girls Aloud singer Kimberley Walsh in the West End adaptation from Wednesday, May 23.
Walsh will make her final appearance on May 21 playing Princess Fiona, the character voiced by Cameron Diaz in the Shrek movies and originally portrayed on stage by Amanda Holden.
Stenson will join a cast that includes Dean Chisnall (Shrek), Richard Blackwood (Donkey) and EastEnders star Neil McDermott (Lord Farquaad).
She previously appeared in the West End adaptation of Legally Blonde, which ended its run last month.
Shrek The Musical celebrates its first year at the Theatre Royal, Drury Lane on Sunday (May 6). Since launching, more than 400 performances have been staged to a total audience of over 600,000 people.