Mary Peters was born in Halewood, Lancashire, but moved to Ballymena (and later Belfast) at age eleven when her father's job was relocated to Northern Ireland. She now lives in Lisburn just outside Belfast.
As a teenager, her father encouraged her athletic career by building her home practice facilities as birthday gifts. She qualified as a teacher and worked while training.
After Ballymena, the family moved to Portadown where she attended Portadown College. The headmaster Donald Woodman and PE teacher Kenneth McClelland introduced her to athletics with Mr McClelland her first coach. She was head girl of the school in 1956.
In the 1972 Summer Olympics in Munich, Peters competing for Great Britain and Northern Ireland won the gold medal in the women's pentathlon. She had finished 4th in 1964 and 9th in 1968. To win the gold medal, she narrowly beat the local favourite, West Germany's Heide Rosendahl, by 10 points, setting a world record score. After her victory, death threats were phoned into the BBC: "Mary Peters is a protestant and has won a medal for Britain. An attempt will be made on her life and it will be blamed on the IRA ... Her home will be going up in the near future." but Peters insisted she would return home to Belfast. She was greeted by fans and a band at the airport and paraded through the city streets, but was not allowed back in her flat for three months. Turning down jobs in the US and Australia, where her father lived, she insisted on remaining in Northern Ireland.
In 1972 Mary won the BBC Sports Personality of the Year award. "Peters, a 33-year-old secretary from Belfast, won Britain's only athletics gold at the Munich Olympics. The pentathlon competition was decided on the final event, the 200m, and Peters claimed the title by one-tenth of a second." http://news.bbc.co.uk/sport1/shared/spl/hi/tv_and_radio/02/sport_personality/past_winners/html/1969.stm
Peters became a Trustee of The Outward Bound Trust in May 2001 and is Vice-President of the Northern Ireland Outward Bound Association. She is also Patron of Springhill Hospice in Rochdale, Greater Manchester.
Peters established a charitable Sports Trust in 1975 to support talented young sportsmen and women, both able-bodied and disabled, from across Northern Ireland. The Trust now known as the Mary Peters Trust, helps aspiring young athletes realise their maximum potential by assisting them in both a financial and advisory capacity. Since its inception more than 40 years ago, the Mary Peters Trust has made a staggering number of Awards making a difference to the lives of thousands of young athletes from across Northern Ireland. The Trust has a very impressive list of alumni including Graeme McDowell, Rory McIlroy, Jonathan Rea, Darren Clarke, David Humphreys, Bethany Firth, Ryan Burnett, Carl Frampton, Paddy Barnes, Michael Conlan, Kelly Gallagher, Michael McKillop, Dr Janet Gray MBE and many more.
Peters was appointed Member of the Order of the British Empire (MBE) in the 1973 New Year Honours for services to athletics, Commander of the Order of the British Empire (CBE) in the 1990 Birthday Honours for services to sport, Dame Commander of the Order of the British Empire (DBE) in the 2000 Birthday Honours for services to sport and to the community in Northern Ireland, and Member of the Order of the Companions of Honour (CH) in the 2015 New Year Honours, also for services to sport and the community in Northern Ireland.
Northern Ireland's premier athletics track, on the outskirts of Belfast, is named after her. A statue of her stands within it.
In April 2009 she was named the Lord Lieutenant of the City of Belfast, retiring from the post in 2014 when she was succeeded by Fionnuala Jay-O'Boyle. Peters is a Freeman of the Cities of Lisburn and Belfast.