Joker: Folie à Deux (Original Motion Picture Soundtrack) reunites composer Hildur Guðnadóttir with writer/director/producer Todd Phillips following their collaboration on the 2019 blockbuster Joker, which took over $1 billion at the global box office and earned Guðnadóttir an Oscar, Golden Globe, Grammy, and BAFTA. For Phillips, the decision to bring Guðnadóttir back to score Joker: Folie à Deux was an easy one. He said, "There was no version of this movie where we weren’t calling Hildur to do the score. I think her music is kind of the second most important character in the first movie."