He was born in London, the son of an advertising copywriter and a barmaid. He used insurance money from his father's death in 1941 for a boarding- school education at Belmont College, Devon, but was expelled after attacking the headmaster.
He became involved in theatre, as a stage manager and then as an actor. He tried his hand at writing plays and two of them (The Devil Inside Her and Personal Enemy) were staged in regional theatres before he submitted Look Back in Anger to the newly-formed English Stage Company at London's Royal Court Theatre. Look Back in Anger, was penned in a mere 17 days.
The play went on to be an enormous commercial success, transferring to the West End and to Broadway, and was later filmed with Richard Burton in the leading role. His next work was The Entertainer (1957), also at the Royal Court and starring Laurence Olivier. Osborne originally aspired to act on-stage, but ended up a journalist and playwright.
Luther (1961) and Inadmissible Evidence (1964) were powerful pieces, using Osborne's characteristically soaring rhetorical venom to powerful effect, but lacing their stories with complexity, ambiguity and richness. A Patriot for Me (1965) was a tale of turn-of-the-century homosexuality and was instrumental in putting the boot in to the eighteenth-century system of theatrical censorship under the Lord Chamberlain.
A Hotel in Amsterdam (1968) was much underrated because, perhaps, of its apparent conventionality, while A Sense of Detachment (1972) was very unconventional, but, for pressing the new avant-garde's techniques into the service of Osborne's by now unfashionable social vision, it was also derided.
Osborne's work was no longer produced by the Royal Court in the 1970s and it faded in quality as the decade wore on. His last play was Deja Vu (1991) a sequel to Look Back in Anger and has some force, but seems self-absorbed and grouchy, lacking the fire of the first play.
As well as plays he also wrote a number of screenplays, mainly adaptations of his own works; he also won an Oscar for his 1963 adaptation of Tom Jones. He acted in a few films, including Get Carter (1971), Tomorrow Never Comes (1978) and Flash Gordon (1980).
In the last decade of his life, Osborne received most praise (and vilification) for the two volumes of autobiography he produced, A Better Class of Person (1981) and Almost a Gentleman (1991), which used that familiar acidity of language to lay low all his enemies, whether in the theatre, his family, or society at large. These included his ex-wife, actress Jill Bennett.
A diabetic and a heavy drinker with a tendency toward irascibility, Osborne was married five times. He died in Shropshire, England, as a result of complications from Diabetes and is buried in the churchyard at Clun.
Osborne's work transformed British theatre. Before Osborne arrived on the theatrical scene, the British theatre consisted mainly of melodramas and drawing-room comedies. He helped to make it artistically respected again, throwing off the formal constraints of the former generation, and turning our attention once more to language, theatrical rhetoric, and emotional intensity.