Music
The 25-year-old's debut album Speech Therapy beat off stiff competition from Florence and the Machine, La Roux and Kasabian to take home the prestigious prize.
She collected her £20,000 winner's cheque from host Jools Holland at a ceremony at London's Grosvenor House Hotel.
Earlier in the evening, Debelle performed 'The Key', a track from her winning album.
According to the Official Charts Company, Speech Therapy has sold fewer than 3,000 copies since its release in August. However, it is expected to experience a sales surge following its victory tonight.
Previous winners of the Mercury Prize, which is voted for by a panel of music industry executives and experts, include Arctic Monkeys, Franz Ferdinand and Pulp.
> Click here to read our review of Speech Therapy
More: Speech Debelle, Music
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