Young Irish actress Saoirse Ronan, who starred in 2007 film Atonement, presented Prouvost the £25,000 ($40,000, 30,000-euro) award for her work, entitled "Wantee".
"Thank you for adopting me, for having a French one, I feel adopted by the UK," said the winning artist.
The four nominees created a typically eclectic collection for this year's prize exhibition in Londonderry, the first time it has been staged outside England.
The often controversial prize was established in 1984 by the Tate gallery in London in honour of 19th-century J. M. W. Turner, who had long wished to set up an award for younger artists.
It is open to any contemporary artist under the age of 50 who is living, working or born in Britain, and is judged on the work they have put on in the last 12 months.