Stanwell, meaning 'stony stream or spring', was held by the Saxon, Azor, in King Edward the Confessor's reign (1042-1066). Azor was one of King Edward's personal guards. The Domesday Survey in 1086 records that Stanwell was the property of Walter, son of Othere, and that the holding included four mills and three weirs where there were eel traps. There was probably a church or chapel at Stanwell before 1066 although none is mentioned in Domesday. The present parish church of St Mary is 13th and 14th century in date and has a well-known leaning spire.

Walter's son, also Walter, adopted the surname of Windsor - a name not used by the present Royal Family until the First World War. The Windsors held the manor of Stanwell until 1543, when they were compelled to hand it over to Henry VIII. In 1603 James I granted the manor to Sir Thomas, later Lord, Knyvett, who had the distinction of being the leader of the party who arrested Guy Fawkes before he could blow up the Houses of Parliament in 1605.

Lord Knyvett founded a free school at Stanwell in 1624 and it was one of the earliest such schools in England. The school building still survives.

Two artificial rivers flow through Stanwell. The Longford River was built during the reign of Charles I (1625-1649) to bring water from the River Colne at Longford to the ornamental water features in the gardens of Hampton Court Palace. The Duke of Northumberland's River is even older. It was apparently built in the reign of Henry VIII (1509-1547) to provide water for a mill at Twickenham. A section of it was diverted when Heathrow Airport was extended.

Stanwell became the property of the Earl of Dunmore in 1720 and in 1752 it was purchased by Sir John Gibbons. The Gibbons family were major landowners in the area until 1933. In 1920 the manor house at Stanwell was purchased by Sir John Gibson, who later became famous as the designer of the Mulberry Harbours, those floating constructions used so successfully during the D-Day landings in France in 1944.