In August 2020, A. R. Rahman was initially approached to compose music for the film. However, Rahman did not sign the film,[3] and was replaced by Mickey J. Meyer.[4] In February 2023, Dutt stated in an interview that Santhosh Narayanan replaced Meyer as the composer of the film.[5][6] Narayanan recorded the background score by February 2024. The recording of songs took place at the Future Tense Studios in Chennai.[7]
In an interview with The Hindu, Narayanan revealed that Nag Ashwin hired him as the music director because he loved the album Cuckoo which was composed by Narayanan back in 2014. Narayanan also stated that he wanted to add tunes of eighties and nineties in the album and said that the album is an ode and tribute to various artists including A. R. Rahman, Ilaiyaraaja, M. S. Viswanathan, S. S. Rajamouli and M. M. Keeravani. Further he stated that the film is set in the future where the remaining people are a mix of languages, cultures and communities. "I wanted to bring that to the album and the score". "Kalki’s album is my ode to the multicultural identity of India.”[11]
The audio rights of the film were acquired by Saregama for all languages.[12] In February 2024, a short glimpse of the theme song of the film was revealed by Narayanan at the Neeye Oli Consort in Chennai.[13] The song "Bujji Theme" was released separately on 27 May 2024.[14][15] The first single titled "Bhairava Anthem" was released on 16 June 2024.[16] The song was sung by famous Punjabi singer Diljit Dosanjh. The song marks Diljit Dosanjh's debut in South Indian film industry and his maiden collaboration with Prabhas.[17] The second single titled "Theme of Kalki" was released on 25 June 2024.[18] The second single titled "Theme of Kalki" featured the Dashavatara of Lord Vishnu.[19] The third single "Ta Takkara (Complex Song)" was released on 29 June 2024.[20] The fourth single titled "Hope of Shambala" was released on 4 July 2024.[21] The song "Keshava Madhava" featured the voice of Amitabh Bachchan (Hindi version) and lyrics written by the duo of Siddharth–Garima in Hindi while Krishna Kanth wrote the Telugu lyrics for the song.[22][23]