Although no dates have been confirmed, the new production will premiere in London and could hit the West End as early as 2013.
Fellowes, who won an Oscar for Gosford Park, is currently riding high with his Emmy-Award winning ITV period drama Downton Abbey, which recently finished its second series.
He said: “The Wind in the Willows is one of our greatest classics, and as true and entertaining now as it has ever been. I am delighted and tremendously flattered to have been asked to write the book for the new musical. In fact, I suspect this is something I’ve been wanting to do subconsciously for many years.”
Stiles and Drewe’s many collaborations include Betty Blue Eyes, which ran in the West End earlier this year, and the Olivier Award-winning Honk!.
George Stiles said: “Ever since working with Julian on Mary Poppins, the three of us have been looking for a new project. We all celebrate our English roots as writers, and the musical possibilities of Kenneth Grahame’s classic chime very strongly with me.”
Anthony Drewe added: “I loved Kenneth Grahame’s novel as a boy and it still resonates with me as an adult, but I suspect it is one of those stories that people ‘think’ they know. There are different depths in the writing as well as some interesting incidents often omitted in other adaptations.”
The Wind in the Willows is being produced by Jamie Hendry Productions, whose recent productions include Legally Blonde the Musical, Birdsong, Spring Awakening and La Cage Aux Folles.