Yasunori Mitsuda was born in Tokuyama in the Yamaguchi Prefecture, and raised in Kumage. As a child, he studied the piano lessons and developed an interest in computers, teaching himself to program simple songs and games on his PC. After enrolling in Tokyo's Junior College of Music, Mitsuda received solid instruction from his professors, most of them practicing musicians, who would take the young composer to gigs, so long as he helped carry the heavy instruments.
In 1992, an advertisement for an opening in the music department at Square was shown to Mitsuda by his friend, Nobuo Uematsu. Mitsuda sent in a demo reel, which won him an interview at the game studio. Despite what he described as a "disastrous" interview, he was offered a position on the company's sound team in April, 1992. He was joined by college friend and fellow musician Yoshitaka Hirota.
Chrono Trigger, Mitsuda's first soundtrack as a composer, was a collaboration with Uematsu, and proved to be popular with fans. The following year he joined Uematsu again for the sidescrolling action game Front Mission: Gun Hazard, working with new recruits to the Square sound team, Junya Nakano and Masashi Hamauzu. Having developed a working relationship with many of the composers and sound designers at Square, Mitsuda's first game project for the Playstation was as producer of Tobal No. 1's soundtrack, which brought together an assortment of musicians. His last contribution to Square was the solo soundtrack for 1998's Xenogears.
Mitsuda went freelance, though he continued to work closely with Square on projects, most notably Chrono Cross. He was the central contributor to the Xenosaga EPISODE I: Der Wille zur Macht soundtrack, and has also released non-mainstream-game music, such as his CD Sailing to the World. Kirite an artistic collaboration with Masato Kato, creator of the Chrono series, features music, art, and stories.
Celtic influences are often evident in Mitsuda's music, particularly so in the Chrono Cross Original Soundtrack and Xenogears Creid arranged album. Apart from his professed love of the Celtic style, Mitsuda's musical classification is difficult to define. For example, the Chrono Cross track "Chronomantic" has elements of Caribbean music, while the song "The Great Sneff's Troupe" has an East Asian flavor. A number of his compositions also resemble traditional Indian music, such as the Chrono Trigger tracks "Corridor Of Time" and "Schala's Theme."