Priestley was born in what he described as an "ultra-respectable" suburb of Bradford. His father was a teacher and his mother died young. On leaving grammar school Priestley worked in the wool trade of his native city, but had ambitions to become a writer. He was to draw on memories of Bradford in many of the works he wrote after he had moved south. As an old man he deplored the destruction by developers of Victorian buildings such as the Swan Arcade in Bradford where he had his first job.
Priestley served during the First World War in the 10th battalion, the Duke of Wellington's Regiment. He was wounded in 1916 by mortar fire. After his military service Priestley received a university education at Trinity Hall, Cambridge. By the age of 30 he had established a reputation as a humorous writer and critic. His 1927 novel Benighted was adapted into the James Whale film The Old Dark House in 1932. His first major success came with a novel, The Good Companions (1929) which earned him the James Tait Black Memorial Prize for fiction and made him a national figure. His next novel Angel Pavement (1930) further established him as a successful novelist. However, some critics were less than complimentary about his work, and Priestley began legal action against Graham Greene for what he took to be a defamatory portrait in Stamboul Train.
He moved into a new genre and became as well known as a dramatist. Dangerous Corner began a run of plays that enthralled West End theatre audiences. His best-known play is An Inspector Calls (1946), later made into a film starring Alastair Sim in 1954. His plays are more varied in tone than the novels, several being influenced by J.W. Dunne's theory of time, which plays a part in the plots of Dangerous Corner (1932) and Time and the Conways (1937).
Many of his works have a political aspect. For example, An Inspector Calls, as well as being a "Time Play", contains many references to socialism — the inspector was arguably an alter ego through which Priestley could express his views . During World War II he was a regular broadcaster on the BBC. The Sunday night Postscript broadcasts through 1940 and again in 1941 drew audiences of up to 16 million; only Churchill was more popular with listeners. But his talks were cancelled, apparently as a result of complaints that they were too left-wing. He chaired the 1941 Committee and, in 1942, he was a co-founder of the socialist Common Wealth Party. The political content of his broadcasts and Priestley's hopes of a new and different England after the war influenced the politics of the period and helped the Labour Party gain its landslide victory in the 1945 general election. Priestley himself, however, was distrustful of the state and dogma.
Priestley was one of the interviewees for the documentary series The World at War (1973), in the episode Alone: May 1940–May 1941.
He was a founding member of the Campaign for Nuclear Disarmament in 1958. He declined lesser honours before accepting the Order of Merit in 1977.
He was married three times. In 1921 he married Pat Tempest, and in 1922 two daughters were born. In September 1926, he married Jane Wyndham-Lewis; together, they produced two daughters and one son. In 1953, he divorced his second wife and married Jacquetta Hawkes, his collaborator on Dragon's Mouth.