The TV and movie mogul worked on the project in secret with Amy Acker, Alexis Denisof and Nathan Fillion.
Little is known about the film, but insiders suggest it will be a modern take on the play.
Acker and Denisof play leads Beatrice and Benedick, while Fillion portrays Dogberry.
Whedon's Much Ado About Nothing is the first feature from Bellwether - the director's new production studio.
Shakespeare's comedy last hit the screen in 1993 when Kenneth Branagh directed his then-wife Emma Thompson, Kate Beckinsale and Keanu Reeves.