The actress starred as Marva in the play, an adaptation of Steve Martin's movie of the same name, when it premiered in Los Angeles last year (10) and was scheduled to take on the role when it heads to Broadway.
But Shields, who is currently appearing in The Addams Family musical in the Big Apple, has exited the project due to other film and television commitments.
In a statement she says, "I'm very disappointed that I'm not able to continue my association with this project. Being a part of Leap of Faith's world premiere was an absolutely thrilling experience. I wish the producers and creative team much success as they prepare to bring this wonderful show to New York."