The Hollywood Reporter confirmed Friday that Wiig and Mumolo will write a live-action musical comedy centering on the characters Anastasia and Drizella.
The new movie is a reimagining of the Cinderella fairytale, which Disney previously adapted as a 1950 animated film.
Deadline said it is unknown whether Wiig and Mumolo will also star in the movie. Sources said the stepsisters will be played by younger actresses.
The film will follow Anastasia and Drizella from their early childhood to Cinderella's marriage and beyond. The sisters will struggle to uphold their family's legacy.
Will Ferrell and Jessica Elbaum will executive produce.
Disney has released or is developing other standalone projects centering on villains, including Maleficent, starring Angelina Jolie, Cruella, starring Emma Stone, and Gaston and LeFou, starring Luke Evans and Josh Gad.
Wiig and Mumolo previously collaborated on the 2011 film Bridesmaids and most recently wrote, executive produced and starred in Barb and Star Go to Vista Del Mar.