The music of Final Fantasy XI was scored by Nobuo Uematsu, Naoshi Mizuta, and Kumi Tanioka. Composer Yasunori Mitsuda was also asked to contribute, but he was busy scoring Xenosaga. The expansion packs were scored by Mizuta alone after Tanioka left to pursue other projects and Uematsu left Square Enix. The opening of the game features choral music with lyrics in Esperanto. According to Uematsu, the choice of language was meant to symbolize the developers' hope that their online game could contribute to cross-cultural communication and cooperation. He also noted the increased difficulty of scoring a game for which there was no linear plotline, a major change from the previous Final Fantasy games. It was the first game in the series for which he composed while he was no longer a Square employee. New music has been employed for special events, such as a holiday score titled Jeuno -Starlight Celebration- which can be heard in the city of Jeuno each mid to late December since 2004. Unlike its immediate predecessor, Final Fantasy XI features almost no voice acting. Vocalizations are portrayed by battle cries and related sounds. Text descriptions are instead utilized to express player communication.
The game's music has been released in CD form several times and has been featured in Final Fantasy concerts. Some of the game's music has been released on iTunes for download, such as the vocal "Distant Worlds", which was released on the Japanese iTunes Music Store on September 13, 2005, having been put in the game in a July 2005 patch. A compilation CD box was released on March 28, 2007, titled Final Fantasy XI Original Soundtrack Premium Box, which included the four original soundtracks from Final Fantasy XI and its three expansion sets, as well as the previously unreleased tracks from the game and the unreleased Final Fantasy XI Piano Collections. Dear Friends -Music from Final Fantasy-, a 2004¨C2005 concert series, featured "Ronfaure" from Final Fantasy XI. A ten-track album of music inspired by Final Fantasy XI entitled Music from the Other Side of Vana'diel was released by The Star Onions on August 24, 2005.