The theme song for the Japanese version of the game, "Kimi ga Iru Kara" (君がいるから, "Because You're Here"), was released as a single by For Life Music in 2009.

The soundtrack received good reviews from critics, who felt that it was Hamauzu's best work to date and an excellent mix of material and genres which took the series' music in a new direction.

[4][5] He tried to match each piece and theme to his sense of the narrative and characters involved in the scenes that they would be played in, and feels that being the sole composer for the project allowed him to ensure that the overall direction of the soundtrack was consistent.

[5] The score features some recordings by the Warsaw Philharmonic Orchestra, arranged by Yoshihisa Hirano, Toshiyuki Oomori and Kunihito Shiina.

[5] Four songs in the soundtrack include vocals by Mina Sakai, an artist whom Hamauzu works as a producer for.

[5] On three of the pieces from the soundtrack: "Sazh's Theme", "Daddy's Got the Blues", and "Can't Catch a Break", described as jazzy pieces related to the character Sazh, Hamauzu's compositions were arranged by Toru Tabei, a friend of his, who Hamauzu describes as being more familiar with that style of music.

[5] The theme song for the international version of the game is "My Hands", from British singer Leona Lewis' second album Echo; it was chosen to replace Final Fantasy XIII's original theme song from the Japanese version, "Kimi ga Iru Kara" (君がいるから, "Because You're Here") by Sayuri Sugawara.

[11] Hamauzu, who composed the music for "Kimi ga Iru Kara", only met Sugawara once, and was not involved in producing the vocal song.

The limited edition of the soundtrack included a bonus disc containing a radio drama written by novelist Jun Eishima.

He applauded Hamauzu's use of motifs and repetition of melodies across different tracks for tying together a widely disparate collection of material, and called the mix of orchestral and electronic pieces as "incredible".

[13] Don Kotowski of Square Enix Music Online similarly approved of the soundtrack, also highlighting the repetition of themes as well done.

[22] Hamauzu came up with the idea for the album originally because he wanted to release the English version of "Pulse de Chocobo" as a downloadable song; when he started adding in promotional tracks and alternative-version tracks he found that he had enough material to release as a full album.

Though he noted that many of the tracks are similar to the originals, he wanted to "bring out subtle properties of the in-game melodies and making them more distinct", rather than greatly change the pieces.

[26] Chris Greening of Square Enix Music Online reviewed the album as "a sophisticated piano collection" that was enjoyable to listen to, though he noted that the arrangements were "straightforward" rather than ambitious.

[27] Gann of RPGFan, however, felt disappointed by the album, calling the arrangements "soul-less" and full of "needless grandiosity".

He concluded that the original pieces were too rich and complex to translate well to solo piano arrangements, which left the works without substance as they did not deviate enough from the source material.

[28] "Kimi ga Iru Kara" (君がいるから, Because You're Here) is the theme song of the Japanese version of Final Fantasy XIII.

"Kimi ga Iru Kara" was released as a single on December 2, 2009 by For Life Music, and included in addition to the piece five other tracks.

While he did not mind "Eternal Love" as much, he still felt that the CD was his least favorite Final Fantasy theme single.

[35] The full Piano Collections Final Fantasy XIII album was played at a concert in 2010: by Aki Kuroda in Osaka on October 29, and in Yokohama on September 3.

[37] All songs in each book have been rewritten by Asako Niwa as beginning to intermediate level piano solos, though they are meant to sound as much like the originals as possible.