Based on the children's book series of the same name by Aaron Blabey, the film stars Brittany Howard as the titular character, alongside the voices of Will Forte, Jemaine Clement, Edi Patterson, Fred Armisen, Zach Galifianakis, Jon Heder and Shondrella Avery.

After humiliating herself at an audition that would have guaranteed them a spot in the singing showcase event SparklePalooza, a clumsy truck driver accidentally drenches Thelma, while wearing a carrot on her forehead, in glitter and pink paint, giving her the appearance of a unicorn.

A blind retired record dealer named Peggy Purvis, after hearing The Rusty Buckets on TV, decides to make them her new comeback attraction.

Two weeks later, Thelma hitches a ride with the driver who instigated her unicorn disguise and reveals that he's been hiding a secret from his girlfriend, as he feels that she wouldn't accept him for who he is.

Suddenly, the driver arrives and accidentally drenches Otis in glue and feathers, giving him the appearance of a pegasus making Thelma burst out with laughter.

In June 2019, it was announced that Netflix acquired the film rights to Aaron Blabey's children's book Thelma the Unicorn after a bidding war, and was developing an animated musical adaptation.

It would be directed by Jared Hess (who wrote the script with his wife Jerusha) and Lynn Wang with Blabey serving as an executive producer alongside Patrick Hughes.

[7] In January 2024, Brittany Howard, Will Forte, Jemaine Clement, Edi Patterson, Fred Armisen, Zach Galifianakis, Jon Heder, Maliaka Mitchell, and Ally Dixon were announced as part of the cast.

Additionally, "Hold On, I'm Comin'" by Sam & Dave, a rerecording of "Conga" by Gloria Estefan, "Diamond Girl" by Nice & Wild, "After Midnight" by Chappell Roan, "Dance Across The Floor" by Jimmy Horne, "Shake Your Pants" by Cameo, "Hollywood Swinging" by Kool & the Gang, "Bodyshakin'" by 911, "Dancing To The Beat" by Clarence Murray, "Slam" by Onyx, "Jump into the Fire" by Harry Nilsson, and Jeff McCollister's "The Hardest Part of Breaking Up" and "Right Where It Counts", are also heard in the film but not included on the soundtrack album.