Her debut album, the critically acclaimed electronica-infused Melankton, was released in March 2006 on iTunes and April 2006 (on physical CD) in Norway only, before being licensed internationally to Universal Republic USA later.

At 14, her goals shifted when she joined an all female punk rock band, rehearsing and playing at Oslo's illegally occupied club Blitz.

In addition to Sigsworth, Havnevik has also collaborated with Marius De Vries, who has previously worked with Björk and David Gray, Yoad Nevo, famous for his work with Welsh singer Jem, LA producer Carmen Rizzo and Petter Haavik from Norwegian techno group Ost&KJex.

As well as her solo projects, Havnevik has also co-written and provided guest vocals on the tracks "Only This Moment" and "Circuit Breaker" by Röyksopp, both featured on the album The Understanding.

She co-wrote and provided vocals on the track "Crazy", featured on mono band's 2005 self-titled LP, a solo project of former Cranberries guitarist Noel Hogan.

Working extensively with Guy Sigsworth, she also provided backing vocals, (as a favor), to a Britney Spears track he produced, which was released in late 2005, entitled "Someday (I Will Understand)."

On 5 December 2006 she made her first ever UK broadcast media appearance, on Janice Long's BBC Radio 2 show, performing "Unlike Me", "I Don't Know You" and "New Day."

Havnevik's vocals are featured on the songs "Don't Go" & " The Fire" from the album "Atemlos" by Schiller, released on 12 March 2010 on iTunes, Germany.

"Lichtblick" was released in November 2010 in Germany, and includes a new song "Ghost", recorded by Havnevik and Christopher von Deylen, especially for it.

In 2010, Havnevik joined the collective "The Dark Flowers" formed by musician/writer/producer Paul Statham who was inspired after reading the "Motel Chronicles" by Sam Shepard and whilst listening to a soundtrack by Bruce Langhorne, from the 1970s western film, "The Hired Hand".

Kate Havnevik wrote, produced and orchestrated 7 songs for the Family Film-musical Mormor og de 8 Ungene in Norway.