The show, written by Downtown Abbey creator Julian Fellowes, is thought to be the first theatrical production to raise £1m through crowd-funding.
It will open at Plymouth’s Theatre Royal on 8 October, and then move to The Lowry in Salford prior to opening in London’s West End.
“I’m happy it’s finally happening,” Lord Fellowes told the BBC.
“A lot of people are interested in the show and have already backed it – so it is something of a weight off my shoulders that it’s finally moving forward.”
The online scheme received investments of up to £5,000, from 400 individuals, the majority of them putting money into a theatre production for the first time.
Lord Fellowes said the scheme was a “new route” for theatre funding and proof of how high Wind in the Willows was in the public consciousness.
“The structures of all our entertainment outlets are beginning to shift,” he said. “Maybe this is a shift in theatre funding and maybe the old thing of the little band that each major producer gathered around them is all coming to an end.”
The show reunites Lord Fellowes with composer and lyricist team George Stiles and Anthony Drewe, whose musical Mary Poppins ran for three years in the West End and six years on Broadway.
Produced by Jamie Hendry and directed by Rachel Kavanaugh, Wind in the Willows will feature the classic characters of Toad, Ratty, Badger and Mole created by Kenneth Grahame.
Another musical written by Lord Fellowes, School of Rock – based on the Jack Black film – is due to open on Broadway this December.
“It’s quite a departure for me,” the Downtown writer admitted. “A rock musical without a ladies’ maid in sight!”