The music of the MMORPG Final Fantasy XI was composed by Naoshi Mizuta along with regular series composer Nobuo Uematsu and Kumi Tanioka. The Final Fantasy XI Original Soundtrack, a compilation of almost all of the music in the game, was released by DigiCube in 2002, and subsequently re-released by Square Enix in 2004. Final Fantasy XI Rise of the Zilart Original Soundtrack was released by DigiCube in 2003 after the release of the Rise of the Zilart expansion for Final Fantasy XI, and re-released by Square Enix in 2004. Final Fantasy XI Chains of Promathia Original Soundtrack was produced by Square Enix in 2004 after the release of the Chains of Promathia expansion, and in 2005 Square Enix published Music from the Other Side of Vana'diel, a collection of arranged tracks from the game performed by The Star Onions, a group composed of Square Enix composers including Naoshi Mizuta, Kumi Tanioka and Hidenori Iwasaki. Final Fantasy XI Treasures of Aht Urhgan Original Soundtrack was released by Square Enix in 2006 for the Treasures of Aht Urhgan expansion.
In 2007, Square Enix released the Final Fantasy XI Original Soundtrack Premium Box, a collection of all of the previously released albums, as well as the as yet unreleased Final Fantasy XI Unreleased Tracks and Piano Collections Final Fantasy XI, an album of unreleased music from the game and its expansions and an album of piano arrangements of music from the game, respectively. After the release of the fourth expansion for the game, Final Fantasy XI Wings of the Goddess Original Soundtrack was released in 2008 by Square Enix. Additionally, in summer 2008 another Piano Collections Final Fantasy XI album, completely separate from the previous piano collections album, will be released by Square Enix.
The music has received mixed reviews; while reviewers have praised some of the associated albums such as Final Fantasy XI Rise of the Zilart Original Soundtrack and Final Fantasy XI Treasures of Aht Urhgan Original Soundtrack, other albums, such as Final Fantasy XI Chains of Promathia Original Soundtrack and Music from the Other Side of Vana'diel, were not as universally liked. Several songs, especially "Distant Worlds", remain popular today, and have been performed numerous times in orchestral concert series, as well as being published in arranged and compilation albums by Square as well as outside groups.