After taking part of some local bands, Kari Rueslåtten joined the cult doom metal band The 3rd and the Mortal with whom she recorded the demo The 3rd And The Mortal in 1993, the EP Sorrow in 1993 and the full-length album Tears Laid in Earth in 1994 through the record label Voices of Wonder. The music was strongly atmospheric mixing progressive and metal elements. She left the band to join the project Storm and recorded Nordavind and her first solo release Demo Recordings, both being Nordic-folk-music styled.

Spindelsinn, her first official solo album came out in 1997 through Sony Norway, sung entirely in the Norwegian language making honour to the folk style shown before. She was also nominated for best vocal artist in the Norwegian Grammy Awards as best female artist at the Norwegian Hit-Awards. The following year, the second release Mesmerised came out. A mellower album, with more personal lyrics in which she left the folk-acoustic style in favour of exploring more modern sounds. The singing style is reminiscent in some parts of Tori Amosmixed with her own style.

Tired of relying on producers to get the sounds she wanted for her songs, she decided to study production and went to London, England for a couple of years. After joining the Swedish label GMR Music Group Kari released a comeback album, the experimental Pilot which contains a lot of modern sounds. It bears some resemblance to Björk, but with the more passionate feel which has always characterized Kari's music. In January 2005, Other People's Stories was issued, showing a simpler side of her music but without losing the modern feel, quality and passion in her performance.

Rueslåtten has also been featured in a handful of drum 'n' bass tracks by the Norwegian duo Rawthang. Her voice is also featured on a very famous classical hardcore record, by Art of Fighters, called "Artwork". This track was included on Dutch Hardstyle DJ, The Prophet´s Dj Mix, "Hard 3".