The Tony nominee, who heads to the big screen next year as Anita in Steven Spielberg's West Side Story, will play Alyssa. The role, played on Broadway by Isabelle McCalla, was previously rumored to go to another Ariana: Ariana Grande.
The Ryan Murphy-helmed film will also star Meryl Streep as Dee Dee Allen, James Corden as Barry Glickman, Nicole Kidman as Angie Dickinson, Andrew Rannells as Trent Oliver, Awkwafina as Ms. Sheldon, Keegan-Michael Key as Principal Hawkins, and Kerry Washington as Mrs. Greene.
DeBose last appeared on Broadway as Donna Summer in Summer, earning a Tony nomination. Her additional credits include A Bronx Tale, Hamilton, Pippin, Motown, and Bring It On.
The Prom, adapted by book writers Bob Martin and Chad Beguelin (the latter also penning the score with Matthew Sklar), is expected to begin filming in December and arrive on the streaming service in fall 2020.