Darvel is known locally as "The Lang Toon," the long town, stretched east-west along the floor of the Irvine Valley at its eastern end. It sits on the A71, the trunk road that runs from Irvine on the west coast to Edinburgh on the east, nine miles east of Kilmarnock. The town is the most easterly of the Irvine Valley settlements, with Galston and Newmilns to the west. People have been here for a very long time. Archaeological surveys between 2003 and 2007, conducted by Glasgow University Archaeological Research Division ahead of an extension to Loudoun Hill Quarry, found evidence of habitation stretching from the Mesolithic to the Late Iron Age. A 2007 excavation uncovered a rare late medieval farmstead, pottery and radiocarbon dates placing it in the 14th and 15th centuries. Roman settlements have been identified at the base of Loudoun Hill on the Allanton Plain. The modern town was laid out in 1754 by John Campbell, 4th Earl of Loudoun, as a source of income for his estate. By 1780 the population had passed 400.

In 1876, Alexander Morton introduced lacemaking to the Irvine Valley. Mills sprang up in Darvel and neighbouring Newmilns, and the valley's textiles were exported around the world. India bought lace, muslin, and madras in particular volume. For about a century Darvel was the Lace Town, its prosperity tied to the looms. The decline was swift. By the late 1970s the industry was struggling against cheaper production in India, China, and the Far East, the very markets that had once been customers. By the end of the 20th century almost every Darvel lace factory had closed. Many sat empty for years before demolition for housing estates. The last lace factory in Darvel has closed; its looms moved to Newmilns, which now holds the only remaining lace factory in the area. The Lace Town that once dressed the world now dresses itself in memory.

The hills around Darvel have carried armies more than once. The 15th-century minstrel Blind Harry wrote in his poem The Wallace that William Wallace and his men defeated an English force at Loudoun Hill in 1296, during the Wars of Scottish Independence, killing in the process the English general Fenwick who had supposedly killed Wallace's father. Maps of the area name a mound east of Loudoun Hill as Wallace's Grave. On 10 May 1307, Robert the Bruce fought and defeated an English force at the same hill. Six centuries later, during the early part of 1944, the 1st Special Air Service Regiment was stationed in Darvel under the command of Lt. Col. Robert Blair Mayne, training for operations behind enemy lines that would precede the D-Day landings. A memorial stone cairn at the bottom of Burn Road commemorates them; it was unveiled by Provost Jimmy Boyd on 2 November 2001 in the presence of SAS veterans.

In Hastings Square stands a curious upright stone about 1.6 metres tall, a piece of olivine listed by RCAHMS as a 'possible' standing stone. The Dagon Stone has twelve small connected depressions across three of its sides, interpreted variously as scratch marks or astronomical alignments. Before the 19th century, newlywed couples and their wedding parties walked sunwise around it for good luck, accompanied by a fiddler. The annual parade or Prawd, held on old New Year's Day, processed sunwise around the stone too. In 1873 the stone was nearly broken up because it obstructed the road; a local farmer rescued it as a cattle rubbing stone before its return to civic prominence. On 23 January 2023, Darvel F.C., the local junior club, beat Scottish Premiership Aberdeen 1-0 in the fourth round of the Scottish Cup. It became one of the competition's biggest upsets. The town, which has produced Sir Alexander Fleming, Sir James Morton the dye chemist, and a roster of footballers, was used to producing the occasional remarkable result. The Aberdeen game just produced the loudest one in a generation.