Daughter of Major Charles Boycott and Betty Boycott née Le Sueur, Rosel Boycott was born in St Helier, Jersey and was educated at the independent Cheltenham Ladies' College and read mathematics at the University of Kent. After working briefly for the radical magazine Friends in 1971, she co-founded the feminist magazine Spare Rib in 1971 with Marsha Rowe. Two years later she and Rowe became directors of Virago Press, a publishing concern committed to women's writing, with Carmen Callil, who had founded the company the previous year.

From 1992-96, she was editor of the men's magazine Esquire. Boycott was the first female editor of two national broadsheets, heading The Independent and its sister publication the Independent on Sunday (1996—98). While editing the Independent on Sunday in 1997, she campaigned for the decriminalisation of cannabis use by individuals,, earning her the nickname "Rizla Rosie". She addressed the Decriminalise Cannabis rally in London's Trafalgar Square on 28 March 1998. Later, she edited the Daily Express (May 1998 - January 2001), leaving soon after the newspaper was bought by Richard Desmond, who replaced her with Chris Williams. She is currently the Travel Editor for The Oldie Magazine and hosts The Oldie Travel Awards each year.

Boycott has made several appearances on Newsnight Review and other cultural and current affairs programmes, where the fact that she is a recovering alcoholic has been discussed. She started drinking heavily again after losing her job at the Express. She was banned from driving for three years in September 2003 after crashing on the A303 in Wiltshire, injuring another driver. She was cut free from the wreckage. A court was told she had also been caught drunk driving the day before.

Boycott has presented the BBC Radio 4 programme A Good Read. She has sat on judging panels for literary contests, notably chairing the panel judging the 2001 Orange Prize for Fiction. She is also a media advisor for the Council of Europe. New Statesman - Full list of judges In September 2007, Boycott appeared in the third series of Hell's Kitchen, and was the first contestant to be voted off.

Boycott is a Trustee of the Hay Festival in the UK and in Cartagena, Colombia.

In March 2002, she denounced the New Labour government as "more reminiscent of a dictatorship than a free healthy democratic system", and announced her support for the Liberal Democrats. She is rumoured to be considering becoming a Parliamentary candidate.

Since her accident, Boycott has been running a farm in Somerset.

On 5 August 2008 she was appointed as the chairman of London Food as part of Conservative Mayor Boris Johnson's attempt to help improve Londoners’ access to healthy, locally produced and affordable food.

In June 2009 she appeared on Celebrity MasterChef.

In June 2009 she was also one of five volunteers who took part in a BBC series of three programmes Famous, Rich and Homeless about living penniless on the streets of London.