Originally opened on 1 July 1842 as part of the Bristol and Exeter Railway, Taunton was the terminus of the line until a new temporary terminus was opened on 1 May 1843 further west at Beambridge.

Isambard Kingdom Brunel's original design was for a single-sided station with two platforms, each with their own buildings and train sheds, placed on the south side of the line.
 A hotel was built between them and the Grand Western Canal.
 Having both platforms on the town side of the line was meant to help passengers but was found to be problematic as the railway became busier, with each train having to cross the line used by trains in the opposite direction.
 An engine shed was provided at the west end of the station.

A series of branches opened in the area during the next thirty years.
 These were the Yeovil branch line (1 October 1853), the West Somerset Railway to Watchet (31 March 1862), the Chard Branch Line (11 September 1866), and the Devon and Somerset Railway (8 June 1871, extended to Barnstaple 1 November 1873).
While none of these branches had a junction in Taunton, the trains were generally run through to Taunton to provide connections.

The station was unable to cope with all these extra trains and passengers, so a major rebuilding was completed on 17 August 1868.
The "up station" at the east end was demolished and replaced by a more conventional platform on the north side of the line; the "down station" was extended onto the site now vacated, and a new single 200 feet (61 m) train shed was provided covering the whole station.
Goods traffic was moved away from the passenger platforms by the opening on 1 November 1896 of a pair of avoiding lines that skirted around the south side of the station behind the old hotel.
A larger engine shed was opened in the same year.

The platforms were extended again in 1895.
Now covering the whole length of the original single-sided station, they were the longest platforms on the Great Western Railway (which had amalgamated with the Bristol and Exeter company on 1 January 1876).
New bay platforms were added to handle the trains from the branch lines.

In the 1930s the lines through Taunton from Cogload Junction to Norton Fitzwarren were widened from two to four tracks; those east of Taunton were brought into use on 13 December 1931 and those to the west on 14 February 1932.
This work forced another rebuilding of the station.
The train shed was dismantled and new buildings constructed on the up (north) side along with a new island platform in the middle of the station.
This gave a platform face for each of the four through lines, which were brought into use on 7 February 1932.
Work included a new subway that replaced the old footbridge, and a new booking office at road level on the north side of the station.
The old goods shed was replaced by a two-storey goods warehouse next to the avoiding line, east of the station on 20 February 1932.

The platforms were numbered:
The down relief platform, principally used by expresses from Bristol
A bay at the east end, used for arrivals from Chard, Yeovil, Castle Cary
The inner bay at the west end, double sided around the single track, principally used for Barnstaple departures
The outer bay at the west end, principally used for Minehead departures
The down main platform, mainly used by expresses from London
The up main platform, mainly used by expresses to London
The up relief platform, mainly used by expresses to Bristol
A bay at the west end, occasionally used for Minehead/Barnstaple arrivals
A bay at the east end, used for stopping train departures to Bristol and Yeovil
Although some no longer have tracks, all the platform structures remain.

Until 1970 the four tracks to the east of Taunton were not used as normal main and relief lines, but with the inner main lines for trains to London and the outer lines for trains to Bristol, to align with the way the tracks diverged at Cogload Junction, some miles to the east of the station.
In 1970 under the Western Region of British Rail the central island platform was closed off and all trains stopping
Originally opened on 1 July 1842 as part of the Bristol and Exeter Railway, Taunton was the terminus of the line until a new temporary terminus was opened on 1 May 1843 further west at Beambridge.
Isambard Kingdom Brunel's original design was for a single-sided station with two platforms, each with their own buildings and train sheds, placed on the south side of the line.  A hotel was built between them and the Grand Western Canal.  Having both platforms on the town side of the line was meant to help passengers but was found to be problematic as the railway became busier, with each train having to cross the line used by trains in the opposite direction.  An engine shed was provided at the west end of the station.
A series of branches opened in the area during the next thirty years.  These were the Yeovil branch line (1 October 1853), the West Somerset Railway to Watchet (31 March 1862), the Chard Branch Line (11 September 1866), and the Devon and Somerset Railway (8 June 1871, extended to Barnstaple 1 November 1873). While none of these branches had a junction in Taunton, the trains were generally run through to Taunton to provide connections.
The station was unable to cope with all these extra trains and passengers, so a major rebuilding was completed on 17 August 1868. The "up station" at the east end was demolished and replaced by a more conventional platform on the north side of the line; the "down station" was extended onto the site now vacated, and a new single 200 feet (61 m) train shed was provided covering the whole station. Goods traffic was moved away from the passenger platforms by the opening on 1 November 1896 of a pair of avoiding lines that skirted around the south side of the station behind the old hotel. A larger engine shed was opened in the same year.
The platforms were extended again in 1895. Now covering the whole length of the original single-sided station, they were the longest platforms on the Great Western Railway (which had amalgamated with the Bristol and Exeter company on 1 January 1876). New bay platforms were added to handle the trains from the branch lines.
In the 1930s the lines through Taunton from Cogload Junction to Norton Fitzwarren were widened from two to four tracks; those east of Taunton were brought into use on 13 December 1931 and those to the west on 14 February 1932. This work forced another rebuilding of the station. The train shed was dismantled and new buildings constructed on the up (north) side along with a new island platform in the middle of the station. This gave a platform face for each of the four through lines, which were brought into use on 7 February 1932. Work included a new subway that replaced the old footbridge, and a new booking office at road level on the north side of the station. The old goods shed was replaced by a two-storey goods warehouse next to the avoiding line, east of the station on 20 February 1932.
The platforms were numbered:
The down relief platform, principally used by expresses from Bristol
A bay at the east end, used for arrivals from Chard, Yeovil, Castle Cary
The inner bay at the west end, double sided around the single track, principally used for Barnstaple departures
The outer bay at the west end, principally used for Minehead departures
The down main platform, mainly used by expresses from London
The up main platform, mainly used by expresses to London
The up relief platform, mainly used by expresses to Bristol
A bay at the west end, occasionally used for Minehead/Barnstaple arrivals
A bay at the east end, used for stopping train departures to Bristol and Yeovil
Although some no longer have tracks, all the platform structures remain.
Until 1970 the four tracks to the east of Taunton were not used as normal main and relief lines, but with the inner main lines for trains to London and the outer lines for trains to Bristol, to align with the way the tracks diverged at Cogload Junction, some miles to the east of the station. In 1970 under the Western Region of British Rail the central island platform was closed off and all trains stopping 
Taunton railway station