She rose to prominence at age nineteen as a member of the indie pop band Belle & Sebastian, but left the group to pursue a solo career, first as the Gentle Waves, and later under her own name.

[2] In 1999, Campbell released her first solo album, The Green Fields of Foreverland, on the same label as Belle & Sebastian, Jeepster Records, under the name the Gentle Waves.

In 2002, she collaborated with Scottish jazz musician Bill Wells on Ghost of Yesterday, a collection of Billie Holiday songs released by Creeping Bent.

[3] Her next album, 2006's Ballad of the Broken Seas, was a collaboration with former Screaming Trees vocalist Mark Lanegan and was well received by critics.

In April 2004, Campbell released an EP with former Screaming Trees and Queens of the Stone Age singer Mark Lanegan, titled Time Is Just the Same.

[4] Lanegan and Campbell played four UK concerts in January 2007, with the London date being moved to a larger venue as a result of high demand for tickets.

[1] The pair toured to promote the album, including a set at All Tomorrow's Parties, 10–12 December 2010 (Bowlie 2) curated by Belle & Sebastian.

In June 2022, Campbell sings in French on an EP called Son Parapluie with Jérôme Didelot, leader of the band Orwell.