He was born in New York to Stanley Patrick Johnson and Charlotte Johnson. He was educated at Eton College, and read Classics at Balliol College, Oxford, where he was president of the Oxford Union.
After working as a management consultant, Johnson became a trainee reporter for The Times in 1987, but was sacked for falsifying a quotation from his uncle. Following a short period as a writer for the Wolverhampton Express and Star he joined the Daily Telegraph in 1987 as leader and feature writer, and from 1989 to 1994 was the paper's European Community correspondent. He served as assistant editor from 1994-1999. His association with The Spectator began with a stint as political columnist from 1994 to 1995. In 1999 he left the Daily Telegraph to become editor of The Spectator.
Johnson is famously disorganised and once explained the lateness of his work by claiming that "Dark forces dragged me away from the keyboard, swirling forces of irresistible intensity and power".
In 2000 Johnson became Member of Parliament for Henley-upon-Thames, succeeding the outgoing Michael Heseltine. He'd previously been unsuccessful in winning Clwyd South in 1997. He married Marina Wheeler in 1993, and has two sons and two daughters.
Johnson has appeared on Have I Got News For You three times, and twice as guest presenter. His autobiography is entitled Friends, Voters, Countrymen, Jottings on the Stump (Harper Collins, 2002).