After returning to Japan, from 1995 to 2003, Rie finished her primary and secondary education in Tokyo. In 2002 she learned guitar, and almost immediately began coming up with songs and recording them with a normal tape recorder. She sent the demo tape off to a record company (Sony) and they signed her. Her first single, Rie who!?, featuring the song "decay", was released in March 2004. Later that year, her song "Life Is Like a Boat" was chosen as the Bleach ending theme, garnering her widespread recognition and demand. In 2005, a year after her debut, another song, I Wanna Go To A Place... was used as the Gundam Seed Destiny third ending song, and in 2006 her song Until I Say was used as the theme to the Japanese release of the 2005 British movie Heidi. In 2007, she performed the ending theme, Tsukiakari, to the anime series Darker than Black.
She graduated from the Central Saint Martins College of Art and Design of the University of the Arts London in fine art (having shifted in interest from fashion design and graphic design) during 2007. She has stated on her website that she would like to become a student again. Rie often designs much of her own album and single booklets, and Rie's own paintings are often featured in them.
Rie fu's songs are often bilingual, since she is fluent in both English and Japanese. Although most of her songs are primarily sung in Japanese, many feature entire verses written in English. Of her songs written entirely in Japanese, several have later been released as English language versions.
On March 3, 2008, Rie fu released an album in the U.K. on a label called Tired & Lonesome. The album, a compilation of earlier songs with one never-before-released Joni Mitchell cover, is entitled "Who is Rie fu?" Though the label is based in England, her album will be released in other European countries marking it her European debut.