The station building was designed by Sir William Tite as a royal station, on a grand scale in Tudor style and, as intended, outclassed the Great Western's wooden shed in every way.

The frontage has stone facings, with a mullioned and transomed main window, gables and a multi-arch entrance. The main booking hall is decorative, but has now been converted into a wine bar. There is a spacious concourse under the train shed at the head of the platforms. The two side platform flank the terminal lines, and extend a considerable distance beyond the train shed.

The wall on the south east (Datchet Road) side of the station forms a long curve, parallel with the platform, containing a series of arches with depressed heads. This wall links the station proper with the former Royal Waiting Room built for Queen Victoria. This is a small building of main room and ante rooms crowned by a turret with spirelet, provided as a look out post for advance warning of the queen's arrival. It has Tudor arched windows, and the interior of the main room has a ribbed ceiling with a pendant finial and a bay window with five angled sections, modelled on the King Henry VII chapel in Westminster Abbey. it is now let as offices.

The original route from Staines was authorised in 1847 to the Windsor, Staines and South Western Railway; it was opened as far as Datchet, on the opposite side of Home Park from the town of Windsor, on 22 August 1848. Opposition from both Windsor Castle and Eton College delayed the completion of the line (there was similar opposition to the Great Western Railway line to Windsor Central), but eventually the Riverside station was opened on 1 December 1849.

In 1848, before Riverside station opened, the Windsor, Staines and South Western Railway had been incorporated into the London and South Western Railway (LSWR), which continued to run services into the station until 1923.