Like most Disney princesses, Ariel has been portrayed as pale-skinned in previous cartoon films, in which she was voiced by white actress Jodi Benson.
Disney came under criticism last year for “whitewashing” Princess Tiana in the cartoon movie Ralph Breaks the Internet, hastily redrawing the character with darker features just months before the film´s release.
Bailey’s casting comes more than two decades after Disney cast singer Brandy, who is also black, as Cinderella in a live-action 1997 film.
Bailey is part of Atlanta-based sister duo Chloe x Halle, who received a Grammy nomination for Best New Artist last year.
Beyonce became a mentor of sorts to them after seeing the pair cover her song “Pretty Hurts” in 2013.
They were signed to her label soon after, and Beyonce took them on her tour in 2016.
Former first lady Michelle Obama is a fan of the duo, turned on to their music by daughters Sasha and Malia.
The Little Mermaid will be the latest in a crop of live-action remakes of classic Disney movies, including the recent Aladdin.
Filming is slated to begin next year.