While at art school in Leeds in 1977, Gartside formed the post-punk band Scritti Politti with schoolmate and friend Nial Jinks and art school friend Tom Morley. After Gartside and Morley had left Leeds Polytechnic, they moved to London, later securing a recording deal with Rough Trade Records who released the first Scritti Politti album Songs to Remember in 1982. However, subsequent Scritti Politti albums featured Gartside with different personnel, with Gartside being the only constant member of the group.

As Scritti Politti, Gartside and New York keyboardist David Gamson and American drummer Fred Maher released the album Cupid & Psyche ’85 in June 1985. The album included hits “Wood Beez (Pray Like Aretha Franklin)” (to the video for which Michael Clark (dancer) lent his contemporary dance); “Absolute” (the video being based on Shakespeare’s A Midsummer Night’s Dream); “The Word Girl”; “Perfect Way”; and “Hypnotize”. Released on Virgin Records it reached number 5 in the UK and was certified Gold by the BPI for 100,000 copies sold. It was produced by Scritti Politti and Turkish-born Arif Mardin who coincidentally also produced Aretha Franklin, one of Gartside’s musical influences.

In 1988 Scritti Politti’s album Provision was a UK Top 10 success, though it only produced one UK Top 20 hit single, “Oh Patti”. After releasing a couple of non-album singles in 1991, as well as a collaboration with B.E.F., Gartside became disillusioned with the music industry and retired to south Wales for more than seven years. Gartside suffered a complete mental breakdown:

In the early and mid 1990s, Gartside lived alone in a secluded cottage in Usk, Monmouthshire, spending his time listening to hip hop, playing darts and drinking beer at his local pub. He returned to music-making in the late 1990s, releasing a new album, Anomie & Bonhomie, in 1999 (which included various rap and hip hop influences).

In 2006, another new album was released by Gartside, the stripped-down White Bread, Black Beer by Scritti Politti, which returned to the more experimental era of the band’s history. He also returned to touring, including his first ever tour of the United States with his band Scritti Politti.

In 2012, Gartside, who has suffered from recurring stage fright that prevented Scritti Politti from touring for many years, performed several songs by Sandy Denny as part of a tribute called The Lady in several UK cities.

In 2015, Gartside was awarded an Honorary Fellowship from Goldsmiths, University of London.

In 2020, Gartside released a solo single on Rough Trade Records, which featured covers of “Tangled Man” and “Wishing Well” by folk singer Anne Briggs.