The show, which is directed by Ed Curtis, features music by Chris Egan and a book and lyrics by Ed Curtis and Guy Jones, and promises "some of the most sophisticated special effects ever seen on stage".
It premieres at the Curve on 6 May 2014 (previews from 24 April), running until 17 May.
Dearman, who was the first actress to play both Glinda and Elphaba in Wicked, will star as the mysterious Mrs D.
Kingsley's 1863 novel centres on the adventures of young chimney sweep Tom, who becomes a 'water baby' when he drowns in a river.
Desperate to get back to the girl he loves, Tom must brave underwater challenges in a world beyond his wildest imagination. Together with the unlikeliest of friends he embarks on a quest to find a way back to land.
Director Ed Curtis' credits include I Dreamed a Dream (UK tour), Jolson & Company (UK tour) and Never Forget (Savoy Theatre and UK tour).
Chris Egan has worked as a composer, arranger and orchestrator on show including The Bodyguard (West End), The Pajama Game (Chichester), End Of The Rainbow (Broadway, West End, US Tour) and Crazy For You (West End).
Besides Wicked, Louise Dearman's other credits include Evita (UK tour), Guys and Dolls (Donmar) and Debbie Does Dallas (Edinburgh Fringe).
Look out for our forthcoming 20 Questions interview with Louise Dearman