Staines-upon-Thames is a town on the left bank of the River Thames in Surrey, England, in the borough of Spelthorne. At or near the Roman settlement of Pontibus, it became Stanes and then Staines. Its borough is in the historic county of Middlesex and its two precursor districts were transferred to Surrey County Council in 1965.

The town is inside the M25 motorway, 17 miles (27 km) south-west of Charing Cross. It is within the London Commuter Belt and the Greater London Urban Area, and adjoins part of the Green Belt. Passing along the edge of the town and crossing Staines Bridge is the Thames Path National Trail. The bridge is one of many re-buildings. It was built from 1827–1832, to white granite-faced designs by George Rennie.

The larger Staines-upon-Thames post town includes the villages of Stanwell, Laleham and Wraysbury. Owing to the long association of Staines Bridge with a medieval causeway (levee) on the opposite bank of the river, the post town also includes part of Egham Hythe. This contains a significant business zone of the county and, in its east, a few of the town’s oldest listed buildings.

Staines-upon-Thames has many parks, leisure centres, a football club and several multinational research/technology company offices. The centre of Heathrow Airport is 3 miles (5 km) to the north-east and Staines railway station is a main stop on the London Waterloo to Reading line and the Windsor & Eton Riverside line.