The official soundtrack to Breath of Fire III was composed by Akari Kaida and Yoshino Aoki, who had previously worked on the music to Mega Man X3. Taking influence from jazz and lounge music, the background themes, Aoki and Kaida relied heavily on synthesized sounds using piano, xylophone, drums, and electric guitar instrumentation. Though many publications found the music Breath of Fire III to be decidedly different from most role-playing game themes, it was met with a largely lukewarm response, with GamePro magazine remarking that music "seems more appropriate for a corporate infomercial than a heroic fantasy RPG".
On September 19, 1997, a selection of tracks from the game were commercially released on the Breath of Fire III Original Soundtrack exclusively for Japan by First Smile Entertainment. The game features the vocal track "Pure Again" as the ending theme, which was performed as a duet by Aoki and Kaida themselves. A commercial for Breath of Fire III which aired only in Japan featured the song "Machi" (街, lit. "City") from the rock group Sophia set against a short animated sequence featuring characters from the game, which was not included in any soundtrack release. Along with all other Breath of Fire series background audio, the music of Breath of Fire III was later re-issued for the first time in its entirety as part of the eleven-disc Breath of Fire Original Soundtrack Special Box in March 2006.