Born in Australia, Crozier grew up in France, learning French. His family then moved to England, where he received a scholarship to study piano and composition at the Trinity College of Music in London. Early in life he believed in communism, as a reaction to the Great Depression and to Adolf Hitler, but later he changed his philosophy and worked to combat it.
Crozier eventually became interested in journalism and pursued a career that led him to become a foreign correspondent for Reuters, a columnist for The Economist, a reporter for the BBC and - during a brief return to Australia - a writer for The Sydney Morning Herald.
Crozier worked as the director of Forum World Features, set up in 1966 by the Congress for Cultural Freedom, which had ties to the American Central Intelligence Agency (CIA). While editing the Economist's "insider" news-sheet Foreign Report, Crozier, as he later recorded in his memoirs, kept some of the best stories that reached him for the CIA. He stated in 1975 that Forum World Features had broken all ties to the CIA when he became its director in the 1960s.
In 1970, Crozier founded the Institute for the Study of Conflict, based in London, to study insurgencies and terrorism. He presided over it for most of the 1970s. According to a profile written by David Rees in 1985 for the American fortnightly National Review "the Institute...was the first private think-tank devoted to the study of terrorism and subversion". Under his direction (he left in 1979) the institute specialised in the study of the "peace-time" strategy of the Soviet Union. Its analyses, including the Annual of Power and Conflict which it published for ten years, have been used in war colleges throughout the West.
For many years Crozier wrote a regular column, "The Protracted Conflict", in the National Review. Joseph D'Agostino of Human Events states: "Crozier has another distinction: in 1988 he appeared in the Guinness Book of World Records for having interviewed the most heads of state or government, 58 in all."
Crozier provided advice to the British Secret Intelligence Service, to the Information Research Department (IRD) of the British Foreign Office, and to the CIA. Lecturing to Britain's staff college for army officers during the early 1970s, when the Labour Party was in power under Harold Wilson, Crozier stated if the government went "too far", it was the armed forces' duty to intervene (he claimed that he was enthusiastically applauded). In 1982 it was revealed from the papers of former Bavarian state security chief Hans Langemann that Crozier was an attendant of Le Cercle and headed a secret international group that tried to influence the West German federal election of 1980 by using secret-service connections and cover-up financial transactions to make Franz Josef Strauß Chancellor of the Federal Republic of Germany.
Crozier was a Distinguished Visiting Fellow on War, Revolution, and Peace of the Hoover Institution. He was also a member of the international advisory council of the Victims of Communism Memorial Foundation. In 1985, he signed a petition in support for the far-right paramilitary Contras (Nicaragua).
- The Rebels: A Study of Postwar Insurrections (1960)
- The Morning After: A Study of Independence (1963)
- South East Asia in Turmoil (1965)
- Franco: A Biographical History (1967) OCLC 438076
- Since Stalin (1970)
- De Gaulle (1973, ISBN 0684129965; reprinted 1990)
- A Theory of Conflict. New York: Charles Scribner's Sons, 1974. OCLC 1514914
- The Man Who Lost China: The First Full Biography of Chiang Kai-shek (1976) ISBN 068414686X
- Strategy of Survival (1978)
- Free Agent: The Unseen War, 1941-1991. London: HarperCollins, 1993. ISBN 0002551926
- The Rise and Fall of the Soviet Empire (1999) ISBN 0-7615-2057-0
- Political Victory: The Elusive Prize of Military Wars. Transaction Publishers. 2005. ISBN 978-0-7658-0290-3.
- "Brian Crozier obituary". Telegraph. 8 August 2012. Retrieved 9 August 2012.
- Joseph D'Agostino (26 November 1999). "Brian Crozier". Human Events.
- David Rees (31 December 1985). "Student of Subversion". National Review.
- "CIA News Service Reported". Washington Post. 3 July 1975.
- Der Spiegel: Victory for Strauß. 37/1982 (PDF Archived 1 May 2013 at the Wayback Machine.)
- "International Advisory Council". Victims of Communism Memorial Foundation. Archived from the original on 22 May 2011. Retrieved 20 May 2011.
- Works by or about Brian Crozier in libraries (WorldCat catalog)
- Brian Crozier papers at the Hoover Institution Archives
- Brian Crozier obituary by Richard Norton-Taylor in The Guardian, 9 August 2012
- Brian Crozier: Intelligence and security expert who fought communism and founded his own spy network, obituary by Chris Bellamy in The Independent, 13 August 2012