Hilary Spurling has won the Whitbread Book of the Year for the second part of her Matisse biography, Matisse the Master.
The writer works as a reviewer for a number of newspapers
In addition to the recognition the award brings, she picked up a cheque for £25,000 at a London ceremony on Tuesday.
Born in Stockport and educated at Somerville College, Oxford, the writer, who is 65, was the arts editor, theatre critic and subsequently literary editor for the magazine The Spectator during the 1960s.
Her first book was a biography of the English novelist Ivy Compton-Burnett, published in two volumes ten years apart.
Ivy When Young, published in 1974, and the follow-up Secrets of Woman's Heart marked Spurling out as a distinguished biographer, with an eye for painstaking detail.
The author then turned her attention to Paul Scott, the award-winning writer of The Jewel in the Crown. The result, Paul Scott: A Life, was published in 1990.
Other biographical subjects include 19th Century French socialite Therese Humbert and George Orwell's wife Sonia Orwell.
'I write biographies because I am fascinated by people - by their infinite resourcefulness, by their mystery and power - by the strange patterns their lives make - and because nature gives me better plots than any novel I could invent," said Spurling.
"My subjects have been writers and a painter because the frontier between life and art is where I like to work."
It is Spurling's weighty two-part biography of the French artist, Henri Matisse, that has brought her worldwide acclaim.
Given unprecedented access to the painter's family correspondence, Spurling's carefully crafted two-part volume was hailed as a "masterpiece" by Whitbread judges earlier this year.
"One of the landmark biographies of the last few years which has already changed the history of art," said the judging panel, including authors Michael Morpurgo and Margaret Drabble.
Spurling lives in London and works as a book reviewer for newspapers including The Daily Telegraph, Observer and New York Times.