Published Thursday, 01 November 2012
The four-piece were bookmakers' favourites to scoop the annual honour for their debut, which was named Britain's best album of the past year at a ceremony in London on Thursday.
Bandmates Joe Newman, Gwil Sainsbury, Thom Green and Gus Unger-Hamilton, who met at university in England, appeared stunned after winning, and embraced one another in a group hug before accepting their trophy and a cheque for £20,000.
Guitarist Sainsbury told fans at the ceremony: "If we get into the whole issue of names (to thank), we could get quite stuck, 'cos I think we've all got a fair buzz on! I think we might just thank everybody in team Alt-J who has ever made a difference."
Alt-J's album triumphed over a shortlist of 11 others, which included Plan B's Ill Manors, Richard Hawley's Standing at the Sky's Edge and releases from Michael Kiwanuka (Home Again), Lianne La Havas (Is Your Love Big Enough?), Ben Howard (Every Kingdom) and Sam Lee (Ground Of Its Own).
Previous winners of the Mercury Prize - established in 1992 to celebrate the best of British and Irish music - include PJ Harvey, Arctic Monkeys, Elbow and Franz Ferdinand.