It branches from the Waterloo–Reading line at Staines-upon-Thames and runs to its western terminus at Windsor via intermediate stations at Wraysbury, Sunnymeads and Datchet.

Most services run between Windsor & Eton Riverside station and London Waterloo via Richmond and Clapham Junction.

[5][a] The buffer stop at Windsor & Eton Riverside is 25 miles 48 ch (41.2 km) down the line from London Waterloo, when measured via Twickenham.

[1] The off-peak service pattern is two trains per hour in each direction calling at all stations between Windsor & Eton Riverside and Twickenham, then Richmond, Putney, Clapham Junction, Vauxhall and London Waterloo.

Its engineer, Charles Vignoles, proposed two lines, one linking the town to Slough and the other to Staines, which would have crossed the Thames together at Romney Island.

[19] The LSWR agreed to lease the line for a 4.5% capital return and payment of half of the operating profits.

[19] A provisional agreement between the WSSWR and the Crown to continue the line to Windsor was reached that month, but was not formalised until 14 February 1849, by which time the extension was under construction.

[19] The WSSWR hoped to be able to open the extension to Windsor during August 1849, but on the 9th of that month, a crack appeared in one of the girders of the Black Potts Railway Bridge, requiring urgent structural repairs.

[19][24][g] As a result of the delay, the GWR, which had obtained authorisation for its own line, opened the first railway station in Windsor on 8 October that year.

[20][27] Designed by William Tite in the Tudor-Gothic style, it included a private waiting room provided for Queen Victoria and her attendants.

[39] Between 1897 and 1940, coal was delivered from the Staines-Windsor line to the Metropolitan Water Board pumping station in London Road, Staines, via a 3⁄4 mi (1.2 km) private siding.

[41] A major resignalling project took place in the mid-1970s, which resulted in the line being controlled from Feltham area signalling centre.

[43] Datchet signal box was retained for three months to operate the level crossing, but closed on 17 December 1974 when control was transferred to Feltham.

The earliest was through the sidings of the Staines Linoleum Company[47] and would have required use of turntables or reversals to pass wagons between the lines.

During the Second World War, a single-track spur was laid from just south of Yeoveney Halt to just west of the site of Staines High Street station, to provide an alternative should cross-London routes be blocked by bomb damage;[48] this link existed from 23 June 1940 to 16 December 1947 but was little used.