The 23-year-old topped the annual industry tastemakers' survey, finishing ahead of second-placed Frank Ocean and Azealia Banks, who finished third.
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Kiwanuka said in a statement: "It's very encouraging for some of my music to be noticed and considered as something worth listening to. I think it's every musician's dream to have any sort of recognition for their art, something that is so personal. This is something that I don't take for granted."
The London Evening Standard's chief rock and pop critic David Smyth paid tribute to Kiwanuka's "rich, warm voice" and the "vintage, psychedelic soul feel" of his output.
Grammy-nominated dubstep producer Skrillex and Swedish dance-pop act Niki & the Dove finished in fourth and fifth place respectively.
Kiwanuka joins previous poll winners including 50 Cent, Ellie Goulding, Little Boots and Jessie J. His debut album Home Again is due for release in March 2012.
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Watch the video to Michael Kiwanuka's track 'Home Again' below: