Long Ditton is a residential suburb in the borough of Elmbridge, Surrey, England on the boundary with the Royal Borough of Kingston upon Thames, London. In medieval times it was a village, occupying a narrow strip of land. Neighbouring settlements include Hinchley Wood, Thames Ditton and Surbiton.

Its northernmost part is 1.5 miles (2.4 km) south-west of central Kingston upon Thames, 11.3 miles from Charing Cross, and 15 miles (24 km) north-east of Guildford. It is divided in two by the South West Main Line and is bordered by a straight east–west spur road to meet the A3 in a cutting to the south. The old Portsmouth Road passes by the River Thames in the northern end of the village, and the riverbank here is privately owned.

In both local economy and public transport, the high street and railway stations at Hinchley Wood and Surbiton are the nearest such amenities.

Ditton was a Saxon settlement which, by the Domesday Book, was a single ecclesiastical parish but split in two, as it remains. This split was between the riverside manor and parish of Thames Ditton, and the longer, eastern area, Long Ditton, which is a long rectangle of land extending from developed land by the River Thames to Ditton Hill. Nowadays Ditton Hill reaches beyond the wide A3 and A309 as far as Woodstock Lane South, much of which is in Claygate parish (and has an Esher postal address).

Two Dittons appear in the Domesday Book of 1086 and were written as Ditone and Ditune. The one that became known as Long Ditton was held by Robert Picot from (i.e. under) Richard Fitz Gilbert. The one that became known as Thames Ditton was held by Wadard under Bishop Odo. Long Ditton's Domesday assets were: 4 hides; 1 church, 1 mill worth 9s, 3½ ploughs, woodland for 15 hogs, 1 house in Southwark paying 500 herrings. It rendered £2 10s 0d.

Henry I granted all four chapelries neighbouring Kingston to Merton Priory, therefore it is uncertain whether the manor had a church or chapel at Long Ditton in that period. Until the early 20th century the parish had two non-contiguous parts, Long Ditton proper and an exclave in Tolworth. A strip of Kingston parish, its hamlet of Hook, lay between the two parts. The western portion, Long Ditton proper, had 896 acres (363 ha) and had near-identical boundaries to today's ecclesiastical parish.

In 1565 the manor was bought by George Evelyn, whose family produced gunpowder here for several generations, with gunpowder mills proliferating across Long Ditton and beyond. The Evelyns bought up much of the country that was heavily involved in the English Civil War, using the profits from gunpowder. George's grandson John Evelyn, who gained posthumous fame for his Diary, had to flee the country during the Civil War as swathes of family land fell awkwardly between Royalist and Parliamentarian strongholds. It was John who gleaned further prestige for the family name with his assimilation into the Royal Court of Charles II. When St Mary's Church was rebuilt in 1880, and monuments erected to commemorate local dignitaries, there were few other Long Ditton figures to celebrate, and the place became something of an Evelyn shrine.

In 1951 the civil parish had a population of 4007. On 1 April 1974 the parish was abolished.