Mansfield's name carries an argument. Historian William Horner Groves wrote in 1894 that it might come from a noble family who arrived with William the Conqueror, or from the Anglo-Saxon Manson meaning trade, or simply from the River Maun. Whatever the origin, by 1042 Edward the Confessor held a manor here, and after 1066 William the Conqueror declared the surrounding Sherwood Forest a royal hunting reserve. King John visited so often between 1200 and 1216 that he built himself a residence at nearby Kings Clipstone, the remains of which still stand. Edward I held a Royal Council in the town. William the Lion of Scotland met Richard the Lionheart at Clipstone to welcome Richard back from the Crusades. The Parliament Oak, on the road between Mansfield and Market Warsop, is said to be where King John and Edward I held informal parliaments under its branches. The market charter of 1227 spelt the town's name Maunnesfeld; a 1377 warrant from Richard II granting tenants the right to hold a four-day annual fair spelt it Mannesfeld. The Royal Manor passed through Edward the Confessor, the Conqueror, King John, Edward I, Queen Isabella, Thomas Howard the third Duke of Norfolk, Bess of Hardwick and her Talbot descendants, and finally the Dukes of Newcastle and Portland.

George Fox walked past St Peter and St Paul's Church one day in 1647 and heard, as he later recorded in his journal, the Lord speaking to him: that which people do trample upon must be thy food. The steeple-house referred to was the medieval parish church mentioned in the Domesday Book of 1086, with much of the surviving fabric Norman. Fox would go on to found the Religious Society of Friends, the Quakers, and Mansfield with him. He met Elizabeth Hooton, a local woman, at her home in Skegby, and Hooton became the first person to accept the doctrines of Quakerism, the religion's first female preacher, and a founding figure in her own right. A Quaker Heritage Trail still runs through Mansfield. The Old Meeting House on Stockwell Gate, built in 1702, is the oldest nonconformist place of worship in Nottinghamshire and traces its founding to 1666, when eight Presbyterian ministers sought refuge in the town under the protection of Reverend John Firth during the persecution that followed the Act of Uniformity of 1662.

The Industrial Revolution turned Mansfield into a textile and coal town. Robert Dodsley, born in 1704 and raised in Mansfield as a stocking weaver, escaped the loom by writing and editing, and went on to publish Samuel Johnson's London in 1738 and to suggest and underwrite Johnson's Dictionary of the English Language. His play The King and the Miller of Mansfield, drawing on local folklore about Henry II hunting in Sherwood and lodging in disguise at Kings Mill, became a minor literary hit in the eighteenth century. The Earldom of Mansfield was created in 1776 for the Scottish lawyer William Murray, who as Lord Chief Justice of the King's Bench presided over the 1772 Somerset v Stewart case, the judgement of which contributed to the gradual abolition of slavery on English soil. The Mansfield family's social and family connections to the Austens are thought to have inspired the title of Jane Austen's Mansfield Park. The Mansfield Brewery rose to dominate the local pub trade with Mansfield Bitter and its slogan not much matches Mansfield. The brewery was bought by Wolverhampton and Dudley in 1999 and closed in 2002. Most of the site became housing; the ornate Chadburn House survives as offices.

Coal mining was Mansfield's twentieth century. May Day 1984 saw a violent episode in the UK miners' strike here, and the town later hosted the breakaway Union of Democratic Mineworkers, which split from the National Union of Mineworkers over the strike. As demand for coal fell, the pits wound down. The Coal Authority itself, the body that took over the legacy of the nationalised industry, is now based in Mansfield. Nikolaos Kotziamanis's larger-than-lifesize statue Tribute to the British Miner, erected in 2003 in the town centre, commemorates the workers whose labour built the town. After the mines came swimming. Rebecca Adlington, born in Mansfield in 1989, learned to swim at the local pool and went on to win two Olympic gold medals in 2008 at Beijing and two bronzes at London in 2012. The Rebecca Adlington Swimming Centre at Sherwood Baths now bears her name, and Mansfield has the largest indoor swimming-water capacity per capita of any UK town under 100,000 inhabitants. Watson Fothergill, the eccentric Victorian architect whose Gothic Revival buildings shaped Nottingham, was born here. So was Alvin Stardust. The town remains the second-largest settlement in Nottinghamshire after the city of Nottingham itself, with a 2021 census population of 110,500 for the wider district.