Tunbridge Wells West station was opened in 1866 by the London, Brighton and South Coast Railway (LBSCR), as the eastern terminus of the Cuckoo Line from Polegate. The station was built as part of a race between the LBSCR and SER conducted during the 1860s for access to the town. The LBSC was becoming concerned at threatened incursions by the SER on its territory.

Tunbridge Wells was first reached from East Grinstead in 1866 via Groombridge. Two years later, with the South Eastern Railway (SER) looking towards Lewes, the London, Brighton and South Coast Railway countered with a line from Groombridge to Uckfield. From Tunbridge Wells West there were direct services to the South Coast at Brighton and Eastbourne and to London Victoria.

The imposing two-storey main station building was designed by C.H. Driver. The station is composed of a central block flanked on the western side by a gable-fronted wing, and on the eastern side by a three-storey clocktower with a pyramidal slate roof surrounded by a louvred cupola with a weathervane. The facade of the building is constructed of red brick with ashlar and black brick dressings; on the ground floor level are a series of nine round-arched windows and an arched doorway, with a decorated ashlar impost band connecting the windows. The eaves are serrated with an ashlar cornice. Inside the building was a gas-lit booking hall with four ticket windows and a panelled ceiling supported by arches springing from stone columns.

The station's facilities were much larger than those at Tunbridge Wells Central. The passenger station originally had five platform roads: three serving long platforms (two of which were island platforms) and two other shorter bay platforms. The reason for the station's extensive layout was that it served no fewer than six different routes: three of which bifurcated at or near Groombridge and two at Eridge.

Although initially conceived as a terminus station, an agreement between the SER and the LBSCR saw Tunbridge Wells West linked by a short spur to the Hastings Line thereby connecting it with the Central station. The spur came about as a consequence of the intense rivalry between the two railway companies which in 1864 had led to both simultaneously depositing bills before Parliament for competing routes across the south-east. The LBSCR obtained authorisation to construct the Ouse Valley Railway, whilst the SER proposed a new line to Eastbourne.

Conscious of the threat that the SER's line would pose to the Cuckoo Line, the LBSCR managed to persuade the SER to withdraw its proposal in return for construction of a spur between the two stations in Tunbridge Wells. A short single-track spur was therefore opened from Tunbridge Wells West through Grove Tunnel after which the track curved north to join the main Hastings Line towards Tunbridge Wells Central, enabling through-running to the Hastings Line and the Brighton Main Line from the West station.