Hughes was born in Sydney, Australia, in 1938. His father and paternal grandfather were lawyers. Hughes's father, Geoffrey Forrest Hughes, was a pilot in the First World War, with later careers as a solicitor and company director. He died from lung cancer when Robert was aged 12.

Hughes left Australia for Europe in 1964, living for a time in Italy before settling in London in 1965, where he wrote for The Spectator, The Daily Telegraph, The Times, and The Observer, among others, and contributed to the London version of Oz. In 1970 he was appointed art critic for TIME magazine and moved to New York, where he soon became an influential voice.  Hughes and Harold Hayes were recruited in 1978 to anchor the new ABC News (US) newsmagazine 20/20. His only broadcast, on 6 June 1978, proved so controversial that, less than a week later, ABC News president Roone Arledge terminated the contracts of both men, replacing them with veteran TV host Hugh Downs. Hughes co-produced, in association with German producer Reiner Moritz and Lorna Pegram, the BBC eight-part series The Shock of the New (1980) on the development of modern art since the Impressionists. It was accompanied by a book with the same title. John O'Connor of The New York Times said, "Agree or disagree, you will not be bored. Mr. Hughes has a disarming way of being provocative."  Hughes's book The Fatal Shore followed in 1987. A study of the British penal colonies and early European settlement of Australia, it became an international best-seller. During the late 1990s, Hughes was a prominent supporter of the Australian Republican Movement.  Hughes's TV series American Visions (1997) reviewed the history of American art since the Revolution. Australia: Beyond the Fatal Shore (2000) was a series musing on modern Australia and Hughes's relationship with it. During production, Hughes was involved in a near-fatal road accident. Hughes's documentary on Francisco Goya, Goya: Crazy Like a Genius (2002), was broadcast on the first night of the new British domestic digital service, BBC Four. He created a one-hour update to The Shock of the New, titled The New Shock of the New, which first aired in 2004. He published the first volume of his memoirs, Things I Didn't Know, in 2006.

Did Hughes go to school?