Icelandic composer Hildur Guðnadóttir's Oscar-winning soundtrack is hauntingly glorious, with many outstanding tracks that fit the film's tone perfectly.
- First is Defeated Clown, a thoroughly depressing song that helps hammer home the feeling of abject failure; not only for Arthur, but for Gotham's general lifestyle. It also brings a foreboding tone, as if this is where the seeds are first planted for Arthur to bloom as the Joker.
- Penny Taken to the Hospital. The tempo and the note variations perfectly capture a person's life falling apart with all their sanity and beliefs fading away.
- Subway starts off quiet and tense, gradually building up into what can only be described as a flourish of unrelenting evil. Unhinged rage flares through the violins and drums, as Arthur violently guns down the three WayneTech employees harassing him - and it is perfectly suiting for Arthur's first major step down into hate-driven madness. It gets a calmer, even more sinister version as Joker exits the subway to go to Murray Franklin's show, and summarizes better than any other track both how steeply Arthur has fallen, and the epitome of evil; the nadir of Gotham City that is the Joker.
- Bathroom Dance is extremely somber and strange, yet it still gives off a blissful, even dreamy feeling as Arthur seems to slowly come to terms with his first murder - finally cementing the first stage of his transformation. The chorus, and the more intense, confident turn the song takes toward the end feels damn near empowering.
- The best one of them all would have to be Call Me Joker, playing in the penultimate scene where Arthur finally lets go of himself to fully become the Joker. The song very slowly builds up, sounding both triumphant and tragic before finally erupting as a powerful symphony that not only closes out Arthur's tragedy, but accompanies the 'happy' ending that he had worked so hard for, and finally finishing the creation of the single greatest, vilest supervillain of all time.
- Gary Glitter's "Rock and Roll Part 2" when Arthur, now fully embracing his Joker persona, goes out on the way to Murray Franklin's show and dances on the stairs.
- Cream's "White Room" when Arthur is hauled away in the police car after murdering Murray Franklin, passing by the rioters torching the city.