Tunstall picked up playing piano and flute at a young age, learned to sing by listening to Ella Fitzgerald, and began writing her own songs in her mid-teens. At 16, she taught herself the guitar and continued to hone her writing skills with sentimental love songs. A scholarship to the Kent School, a private prep school in Connecticut, brought her experiences outside of St. Andrews and Scotland. She formed her first band there, the Happy Campers, and enjoyed seeing shows by 10,000 Maniacs and the Grateful Dead. Next came a music course at London's Royal Holloway College, before heading back home and immersing herself in the local grassroots scene that birthed bands like the Fence Collective and the Beta Band. Around this time, KT was also listening to a lot of Billie Holiday, Lou Reed, and James Brown, among others, and soon formed a group with the Fence Collective's Pip Dylan.

Fast forward a few years. KT returned to London and began writing more songs, many of which would appear on her subsequent album. She entered a backwoods Wiltshire studio with minimal instruments in tow and Steve Osborne (U2, New Order) at the controls. The end result was her glossy debut, Eye to the Telescope, released in the U.K. in January 2005 on Relentless. Highlighting her soulful voice, sassy attitude, and earthy songwriting approach, comparisons to Dido, Fiona Apple, and Kate Melua soon sparked. Following the record's release, Tunstall hit all over Europe, including shows supporting Joss Stone and singing with Oi Va Voi. Feeling an acoustic guitar was sometimes too limiting, her live show incorporated the use of an Akai Headrush foot pedal that allowed her to spot-record multiple times (loop each section continuously), thus turning Tunstall into her own one-woman backup band.

Early 2006 continued to be bright for Tunstall as Telescope was released in the United States that February, and she won Best British Female Solo Artist at the Brits. Meanwhile, her first single, "Black Horse & the Cherry Tree," continued to do very well on American adult alternative radio. KT Tunstall's Acoustic Extravaganza was issued that fall; it included acoustic tracks (both new and old) recorded the previous Christmas along with a bonus making-of DVD. In 2007 Tunstall returned to the scene with her poppier Drastic Fantastic. Three years later, Tunstall recorded her third album, Tiger Suit, at Berlin's Hansa studio, the same place where David Bowie recorded Heroes. The album appeared in the fall of 2010.