The soundtrack was composed by Rodriguez as well as John Debney and Graeme Revell. The film's three main stories ("The Hard Goodbye", "The Big Fat Kill", and "That Yellow Bastard") were each scored by an individual composer: Revell scored "Goodbye", Debney scored "Kill", and Rodriguez scored "Bastard". Additionally, Rodriguez co-scored with the other two composers on several tracks.
Another notable piece of music used was the instrumental version of the song "Cells" by the London-based alternative group The Servant. The song was heavily featured in the film's publicity, including the promotional trailers and television spots, as well as being featured on the film's DVD menus.
"Sensemayá" by Silvestre Revueltas is also used on the end sequence of "That Yellow Bastard". Fluke's track "Absurd" is also used when Hartigan first enters Kadie's.