Blake, a 25-1 outsider to win, is a Goldsmiths College music graduate who was previously nominated for the Mercury for his self-titled debut album which he recorded at his home in New Cross, south east London.
Accepting his award, he said it was "amazing" to be in the running for an award with chart veteran David Bowie.
Asked what he would spend the money on, he said: "I'll make sure it goes to some good use".
He added: "This is the first award I've ever won apart from a tennis trophy which I won when I was about 12-years-old at my school and I'll hold them in equal esteem".
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The 2014 ceremony will take place at Wembley Arena on October 22, returning to the city where the awards started in 1996.
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