Grossman was born in Marblehead, Massachusetts on 16 September 1950, the son of David K. Grossman and Helen Katherine (née Gilman). His initial education was at the General John Glover School in Marblehead, and then at Marblehead High School. He graduated from Boston University with a Bachelor of Arts degree in history before traveling to the United Kingdom in 1975 to study at the London School of Economics where he received a master's degree in economic history. He later returned to university at Magdalene College, Cambridge, where he studied history of art, receiving both a master's degree and a PhD.
Grossman has an ongoing career as a singer initially with punk band Jet Bronx And The Forbidden, who reached number 49 in the UK singles chart in December 1977 with "Ain't Doin' Nothing". He returned to playing music in 2008. Following a guest appearance playing "Ain't Doin Nothin" with the Pork Dukes at the Vienna Rebellion punk festival on 27 April 2008, he played with his new band Jet Bronx and the New Forbidden at the 2008 Rebellion Festival in Blackpool and at Glastonbury in 2012 and 2014.
Grossman became a restaurant reviewer for Harpers & Queen and The Sunday Times.
Grossman's television début came in April 1987, as a roving presenter for Through the Keyhole, a programme examining the homes of the famous. Before leaving in 2003, Grossman made almost 400 appearances on the programme. In July 1990, he became the first presenter of MasterChef, which he presented for 10 years (apart from a year off), also fronting the children's version from 1995 until 1999. Other programmes include the History of British Sculpture (2003), and cookery show Step up to the Plate (2008).
Grossman won an edition of BBC's Celebrity Mastermind on 27 December 2009. His specialist subject was 18th Century art and artists.
From 1995 Premier Foods have produced the Loyd Grossman sauces brand of cooking sauces under licence.
In 2000, he was appointed to head the £40 million project to improve the quality of food served in British NHS hospitals and visited the Norfolk and Norwich University Hospital in December 2002 to raise awareness of the Better Hospital Foods project.
Grossman's lifelong interest in history, the arts and heritage has involved him in a number of organisations. He is a former Commissioner of the Museums and Galleries Commission, a former Commissioner of English Heritage (where he was Chairman of the Museums Advisory Committee and the Blue Plaques Panel), a former Commissioner of the Royal Commission on the Historical Monuments of England, a founding member of the Museums, Libraries and Archives Council, past Chairman of the National Museums Liverpool and of the Public Monuments and Sculpture Association. He founded the 24 Hour Museum (now Culture 24) and was its Chairman until 2005.
Grossman is Patron of the Association for Heritage Interpretation, Patron of Heritage Open Days, Patron of the Haslemere Educational Museum, Patron of the Historic Lincoln Trust, Patron of the Cavell Nurses' Trust and Patron of the American Museum in Britain. He was also Patron of Latymer Sub-Aqua Club for People with Disabilities from 1995 until its demise in 2013. He is President of NADFAS, Deputy Chair of The Prince's Drawing School, President of the British Association of Friends of Museums and a Fellow of St Deiniol's Library. He was Chairman of the University for the Creative Arts from 2008 to 2012, a member of the Court of Governors of the LSE from 1996 to 2009 and is now an Emeritus Governor of the LSE. He is a Member of the Council of the British School at Rome, a member of the board of the Association of Leading Visitor Attractions and Governor of the Building Crafts College.
In 2007, Grossman was appointed Chairman of The Churches Conservation Trust and in 2009 he was appointed Chairman of The Heritage Alliance, the UK membership organisation that represents more than 100 leading non-governmental organisations across the heritage sector. In 2015 he was re-elected for an unprecedented third term as HA Chair.
He is a member of the Court of Assistants of the Company of Arts Scholars, an Honorary Liveryman of the Worshipful Company of Glaziers, a Liveryman of the Worshipful Company of Carpenters, a Fellow of the Society of Antiquaries, a Fellow of the Society of Antiquaries of Scotland, a Fellow of the Royal Society of Medicine and a Fellow of the Royal Society of Arts.
He was married to Deborah Puttnam, the daughter of the film producer David Puttnam, and has two daughters. The couple divorced in 2004. His interests include scuba diving (in which he is a PADI-qualified Divemaster), tennis, chess, fishing and music. He is also a fan of the Boston Red Sox. He is a member of a few private members' clubs, including Brooks's, The Hurlingham Club and the Chelsea Arts Club.
His Mid-Atlantic accent reflects his Boston origins as well as the many years he has spent in the UK. It is often the subject of parody including in adverts for his own sauces, where home cooks imitate his speech as they use sauces that are promoted as having a "distinctive voice."
In 1996, Grossman was awarded a Glenfiddich Food and Drink Award for his involvement in the MasterChef television series. He was awarded an OBE in 2003. On 9 November 2007, he became an Honorary Graduand of the University of Chester where he was presented for admission to the degree of Doctor of Letters, honoris causa. He was granted armorial bearings by letters patent of the English College of Arms on 5 March 2004. In 2011 the University of Lincoln awarded him an honorary Doctor of Arts degree in recognition of his contribution to the cultural heritage sector.
In 1995, Grossman was parodied in the BBC comedy The Smell of Reeves and Mortimer featuring a sketch based on the Masterchef programme. Vic Reeves comedically portrays Grossman with a huge bulbous head floating around the studio to the sound of bells, judging the contestants' catering efforts.The Social History of Rock Music (1975)
Harpers and Queen Guide to London's 100 Best Restaurants (1987)
The Dog's Tale (1993)
Loyd Grossman's Italian Journey (1994)
Courvoisier's Book of the Best (1994–96) - as editor
The World on a Plate (1997)
The 125 Best Recipes Ever (1998)