Lawson was educated at St Columba's College in St Albans and took a degree in English at University College London, where his lecturers included John Sutherland and A. S. Byatt.
Lawson has been a freelance contributor to numerous publications since 1984, beginning on The Universe in that year, and for The Times from 1984 to 1986. He has written a column for The Guardian since 1995, having previously written for The Independent (1986—95), and has twice been TV Critic of the Year as well as winning many other journalism awards. His Guardian journalism has not been universally admired though. A former colleague Richard Gott, who chose to resign in an expenses scandal, has commented that the "prevalence of the bland and the obsequious" on The Guardian is typified by Lawson's "embedded presence".
Lawson presented The Late Show on BBC2 in the 1990s and presented its offshoot The Late Review (later Sunday Review and from 2000 Newsnight Review) until the 2005 'review of the year' edition of Newsnight Review, broadcast on 16 December, which marked the end of his association with the format. In 2004, Lawson made a documentary for BBC Four called The Truth About Sixties TV, criticising what he called "golden ageists" who, he claimed, have a rose-tinted view of television's past.
Mark Lawson is one of the regular presenters of BBC Radio 4's daily arts programme, Front Row. He has written several radio plays for the network, including St Graham and St Evelyn (2003) on the friendship between the Catholic novelists Graham Greene and Evelyn Waugh and The Third Soldier Holds His Thighs (2005) on Mary Whitehouse's campaign against the Howard Brenton play The Romans in Britain. He has also written episodes of the television version of the BBC sitcom Absolute Power appearing as himself in the series 1 episode 2, Pope Idol, and is one of many celebrities impersonated by the Dead Ringers team, referred to as "Britain's brainiest potato" and "the thinking woman's potato" because of his baldness. In 2002, Viz ran a spoof of his Newsnight Review programme, featuring Mr Lawson engaged in a desperate search for hard-core pornography, entitled "The Artful Podger".
Since 2006, he has hosted a number of in-depth, one-to-one interviews for BBC Four, entitled Mark Lawson Talks to... .