Barber attended Lady Eleanor Holles School in south-west London. While she was studying for her A levels she had a two-year relationship with a significantly older man, whom she knew as Simon Goldman, but who also called himself Simon Prewalski. He was an associate of Peter Rachman, and he deceived both Barber and her parents.[clarification needed] This affair subsequently provided the basis for a memoir by Barber and a film based on the memoir (see under Career below).
Barber read English Language and Literature at St Anne's College, Oxford, where she was briefly the girlfriend of the drug smuggler Howard Marks, but also met David Maurice Cloudesley Cardiff, whom she married in 1971. The couple had two daughters. Cardiff died in August 2003.
Barber worked for Penthouse for seven years until 1974, being successively editorial assistant, literary editor, features editor and deputy editor; she left to have children. From 1982 to 1989 she was a feature writer on the Sunday Express magazine, and she then joined The Independent on Sunday before its launch in 1990. Barber has also written for Vanity Fair, The Sunday Times, The Daily Telegraph and, from 1996 to 2009, The Observer.
Barber is best known for her interviews. She was once quoted by Will Self as describing her method as "start[ing] ... from a position of really disliking people, and then compel[ling] them to win you over." An interview with the conceptual artists Jake and Dinos Chapman was not a success, and she claims the Chapman Brothers have threatened to kill her if they ever meet again. Barber is also remembered for her 2001 article about a chaotic meeting with singer Marianne Faithfull. 
Barber has won six British press awards. Her books include two collections of interviews, Mostly Men and Demon Barber, a sex book How to Improve Your Man in Bed, and a survey of Victorian popular natural history writers, The Heyday of Natural History.
Barber's memoir of her teenage love affair, An Education, was published in June 2009. Its genesis was in a short piece on a similar theme that Barber wrote for the British literary magazine Granta. Nick Hornby adapted this short article as a film with the same title, made by BBC Films and released in October 2009, and available on video from March 2010. In the meantime Barber had expanded the Granta article into her memoir, too late for Hornby to use it as source material for the film.
In 2009, Barber returned to The Sunday Times to write for its magazine.
In July 2011, Barber was successfully sued by Sarah Thornton for libel and malicious falsehood over Barber's review of Seven Days in the Art World, published in The Daily Telegraph on 1 November 2008.
A memoir of Barber's career as a celebrity interviewer, A Curious Career, was published in May 2014.
- Barber, Lynn (2009). An Education. London: Penguin Books. pp. 8 et seq. ISBN 978-0-14-103955-8.
- Barber, Lynn. "An Education". Granta. Retrieved 29 July 2020.
[...]me and my disciples at Lady Eleanor Holles School[...]
- Barber, Lynn (7 June 2009). ""My Harsh Lesson in Love and Life,"". The Observer. Retrieved 21 March 2010.
- Lynn Barber, "Memoirs of a Swot who Went to Pot", Daily Telegraph, 7 September 1996.
- Hugh Cecil, "Obituary: David Cardiff," The Guardian, 29 August 2003.
- Lynn Barber, "Almost As Many Balls as Breasts", The Observer, 21 January 2007.
- Dennis Griffiths (ed.) The Encyclopedia of the British Press, 1422–1992, London & Basingstoke: Macmillan, 1992, p.88.
- Peter Ross, "La Grande Dame Inquisitor - The Interview: Lynn Barber", Sunday Herald, 25 March 2007, as reproduced on the website Find Articles.
- Lynn Barber, An Education, London: Penguin, 2009, pp. 113-14.
- Stephen Brook, "Lynn Barber to Leave Observer," The Guardian, 17 September 2009.
- Will Self, "Interview: The Doll Within", The Independent, 25 April 1999, accessed 21 December 2009.
- Lynn Barber, "How I Suffered for Art's Sake," The Observer, 1 October 2006; accessed 3 August 2008.
- Barber, Lynn (Summer 2003). ""An Education"". Granta. 82: 203–223.
- Interview with Lynn Barber on Front Row, BBC Radio 4, 2 February 2010.
- England and Wales High Court (Queen's Bench Division) Decisions accessed 22 March 2013.
- ""Telegraph Refused Appeal over Lynn Barber Review Libel"". Press Gazette. 24 February 2012. Retrieved 29 September 2012.
- Spurling, Hilary (1 May 2014). "A Curious Career by Lynn Barber – review" – via www.theguardian.com.
- "Roll of Honour". Press Gazette. 16 June 2011. Archived from the original on 16 June 2011.