Rythem's talents as singer/songwriters, with flowing melodies and harmonies, began to shine as they worked with their own original tune "Hitoritabi Shararuran" in the Sony Music Audition. In May 2003, Rythem's first single "Harmonia" was released and was used as the second ending theme song for hit TV TOKYO anime series, Naruto. Following the successful release of their debut single, 4 more singles and the debut album, Utatane were released before "Hōki Gumo" was released in early 2005 as a single for the first opening theme of yet another hit TV TOKYO anime series, Yakitate!! Japan.

The 8th single, "20 Tsubu no Kokoro" was a collection of tunes written and performed each by Yui and Yuka dedicated to each other. The 9th single, "Kokoro Bīdama" was used as the 6th and final ending theme song of Yakitate!! Japan, rounding up their involvement with that anime series. The 10th single will be titled "Negai" and will be used as the ending theme of Nippon TV show Sukkiri (スッキリ). Rythem's 2nd album and coinciding DVD was released in May and June 2006, respectively compiling their works, post-UTATANE as well as including some full length versions of short pieces which were performed on their weekly radio show Enjoy Your Time!.

Busily promoting new up and coming talent, Rythem then headed out in late 2006 to perform a series of live concerts entitled "Acoustic PoP". With their busy schedule on the road, Rythem managed to pull out one single in time for the Spring season and the plentiful visual sights of cherry blossoms, named Sakura Uta (or 'song of the cherry blossoms') in early 2007. As well as being a tie-in for the anime series Deltora Quest (first ending theme), this single also marks the beginning of the "Third Stage" or Rythem's venture into the music arena.

As Summer quickly dawns, a 12th single has been announced to reflect the atmosphere of the season once again - Hotarubi or 'firefly'. Hotarubi was initially scheduled for release in August 2006, but was postponed for further tweaking in the areas of lyrics and arrangement. Their latest album, 23 was released on October 1, 2008.

Both two member has written songs for other artists: Yuka had written two songs, "Moment" and "I my me", for Yui Horie. She also wrote the lyrics for all the songs (and composed a few) of Rie Tanaka's album, Kokoro, which was out on October 20, 2010. Yui had also contributed a composition ("Frame") for the same album of Tanaka's and wrote "Milk" for Rina Sakamoto. However, she also recorded a duet ("Laundry") with Rie fu this year for said artist's album, at Rie sessions.

It was announced on October 24, 2010 on a live streaming video that all activities of Rythem will end on February 27, 2011, after the group's "Final Fantasy Live: The Best Rhythm in Rythem's History" performance on that day. Their last single, "A Flower", was released on November 10, 2010. The music video has the word "Fin" at the end. Their final album, Rythem, was released on December 8, 2010.

A complete box set of 5 Blu-spec CDs and 5 DVDs, "RYTHEM COMPLETE BOX～Music of the people, by the people, for the people", is scheduled for release on 25 May 2011. It has a full collection of all their songs (a total of 72), including a new one called "Ai no Kotoba" (Words of Love). The DVDs contain all their music videos, footage of their final live performance, documentaries of their 7 years of publicity and interviews. Along with the 10 discs, the box ships with a booklet and a pair of character figurines of the duo (designed by YUI herself).

In the official announcement on their homepage, Yui and Yuka stated that they will use their full names to perform music in the future. Yui and Yuka have already began work as solo artists, with Yui changing her stage name to "Neat's".[1] Yuka mentioned in an update to subscribers of her mailing list on 11 March 2011 that she has been recording demos, and it was announced that YUI will perform in a charity event, "＆SACHI vol.HOPE", on 24 May 2011 as a guest.