The songwriters behind the 4*Town's songs are singer Billie Eilish and her brother, singer and producer, Finneas. Finneas touched on their excitement to work on music for the movie, saying in the "Welcome to 4*Town" music featurette, "When we got approached about this project, we leapt at the opportunity." Billie noted in the featurette that she had a special connection to the characters, saying, "It really resonated with me because I was the same… [Its] so accurate of how it feels when you're that kind of fan… I just- I love the film."
Finneas's involvement in the movie goes beyond just writing the music. He also voices the 4*Town member Jesse.