Hamauzu was hired by Square as a trainee, and his debut as a solo composer came the following year when he scored Chocobo's Mysterious Dungeon.

[1] Hamauzu grew up in Germany and started to receive piano and singing lessons from his parents at very young age, and when he was in high school, he composed his first original music piece.

[1] A fan of the Final Fantasy games,[3] Hamauzu decided to apply for a job at Square, where Nobuo Uematsu hired him as a trainee in 1996.

[1] Shortly after the title's release, Hamauzu and Yasuo Sako created Chocobo no Fushigina Dungeon Coi Vanni Gialli, an arranged album containing orchestral tracks from the game's music.

For Final Fantasy VII, Hamauzu was the synthesizer programmer for the rendition of Joseph Haydn's "The Creation", and provided bass vocals in the eight-person chorus for "One-Winged Angel".

[1] In 2002, Hamauzu composed the music for Unlimited Saga, a game that would be received negatively by critics due to a variety of gameplay issues.

[17] The album was well received by fans, and helped confirm Hamauzu's position as a leading piano arranger of video game music.

Outside of the Final Fantasy series, Hamauzu also wrote music for games such as Half-Minute Hero: The Second Coming, The Legend of Legacy, and The Alliance Alive in the 2010s.

[24][25] He contributed arrangements to the Across the Worlds ~ Chrono Cross Wayô Piano Collection album alongside Akio Noguchi and Mariam Abounnasr.

[27] In Unlimited Saga, for example, the style of his compositions mix classical marches, tango music, electronic ambiance, instrumental solos, bossa nova, and jazz.

[28] He cites animation composers Hiroshi Miyagawa and Ryuichi Sakamoto of Yellow Magic Orchestra and his father as major musical influences.