The 1969 heist classic, about a group of criminals who attempt to steal a van full of gold, notched up 15 per cent of votes in a survey of 1,000 film fans to find the best movie to come out of the U.K.
Monty Python's Life of Brian came in second, while The Full Monty trailed in third with six per cent of votes in the Sky Movies HD poll.
Meanwhile, Sir Anthony Hopkins was crowned Britain's favourite actor with 12 per cent of the vote and Laurence Olivier was a close runner-up with 10 per cent. The Italian Job's lead actor Caine rounded out the top three.
Dame Judi Dench was hailed the country's top actress with a quarter of the votes cast, while her closest rival, Dame Helen Mirren, took 14 per cent.
Rear Window director Alfred Hitchcock was voted Britain's best filmmaker.
Ian Lewis, Director of Sky Movies, says, "The results of the Greatest British Film poll speak volumes about the nation's favourite homegrown talent, and the dream line-up would be a truly spectacular film. As we approach awards season and the competition escalates, we wanted to celebrate the best of British talent... We are rooting for the likes of Colin Firth, Helena Bonham Carter and Christopher Nolan during this year's awards."