In 1784, General William Roy set out the baseline of what would become the Ordnance Survey across Hounslow Heath, passing through Feltham. General Roy is commemorated by a local pub. The MOD Defence Geographic Centre still has a base in Feltham, used as a government mapping office.

In 1831 Feltham occupied an area of 2620 acres, stretching into Hounslow Heath and had a population of 924. Feltham railway station was opened in 1848 by the Windsor Staines and South Western Railway (later the London and South Western Railway). By 1901 the parish had a population of 4534.

The main economic activity of the Feltham area was market gardening until well into the twentieth century. A popular variety of pea known as the Feltham First is so-named for being first grown in the town. The market gardens were largely replaced with light industry, gravel and aggregate extraction, and new housing from the 1930s onwards.

Feltham has been associated with land and air transport for more than a century. Feltham was in the early and mid 20th century home to Britain's second largest railway marshalling yard which was geared towards freight, and was a target for German air force bombs several times during World War II. The motor car manufacturer Aston Martin had its main factory in Feltham between 1926 (when it bought the former Whitehead Aircraft factory) and 1963.

Opened as early as 1910, Feltham Young Offenders' Institution or HM Prison Feltham is a major such institution providing a range of employments and rehabiliation schemes for young people near the town's border with Ashford and the neighbouring village of East Bedfont.

Famous former resident Freddie Mercury (born Farokh Bulsara in Zanzibar, 1946–1991) of rock band Queen was commemorated by a permanent, Hollywood-style granite star in Feltham's town-centre piazza, unveiled on 24 November 2009 (the eighteenth anniversary of Mercury's death) by Queen guitarist Brian May, alongside Freddie's mother, Jer Bulsara, and his sister.