London-based Barnes, whose novels were shortlisted on three previous occasions for the Man Booker prize was fourth time lucky and was the bookies favourite to win, but had once described the prize as 'posh bingo'.
Barnes was previously nominated for the prize thrice, but without success, in 1984 for 'Flaubert's Parrot', in 1998 for 'England, England' and in 2005 for 'Arthur and George'.
Critics accused the five judges of dumbing-down after chairperson Stella Rimington said the finalists had been chosen for readability.
She defended the choice of the short-listed six books during the announcement at London's Guildhall last night. In a scathing comment, Jeanette Winterson wrote in The Guardian: 'Ignore the Booker brouhaha. Readability is no test for literature. Novels that last are language-based novels - the language is not simply a means of telling a story, it is the whole creation of the story. If the language has no power - forget it.'
She added: 'I am sorry that the Booker judges were thrilled to be seen as champions of the jolly good read. This year's Booker prize isn't about the power of the new - there's no experiment with form or strangeness of imagination.
The winner may get on the bedside tables of middle England, but that's not as important as changing the way that even one person dreams'.
Announcing the winner from the short-list of six books, Rimington said: 'It is a beautifully written book. We thought it was a book that spoke to humankind in the 21st Century.'
The other nominees for the prize were Carol Birch ('Jamrach's Menagerie'); Canadians Patrick deWitt ('The Sisters Brothers') and Esi Edugyan ('Half Blood Blues'); and debut authors Stephen Kelman ('Pigeon English') and AD Miller ('Snowdrops').
Rimington said: 'Julian Barnes' 'The Sense of an Ending' has the markings of a classic of English Literature. It is exquisitely written, subtly plotted and reveals new depths with each reading.'
Barnes is the author of ten previous novels, three books of short stories and three collections of journalism. Now 65, his work has been translated into more than thirty languages.
Over and above his prize of 50,000 pounds, Barnes can expect to bring his novel to wider audiences around the world who follow the winners of the Man Booker Prize.
Each of the six shortlisted authors, including the winner, receives 2,500 pounds and a designer-bound edition of their book.
The judging panel for the 2011 Man Booker Prize was: Dame Stella Rimington (Chair), author and former Director-General M15; writer and journalist, Matthew d'Ancona; author, Susan Hill; author and politician, Chris Mullin and Head of Books at the Daily Telegraph, Gaby Wood.
Sales of the shortlisted books have been the highest selling since records began. Sales of the novels are up 127 per cent year-on-year and up 105 per cent on the previous record in 2009, organisers said.