The 6 km (4 miles) Metropolitan Railway originally ran from Farringdon to Paddington and was the world’s first underground railway. It operated with steam locomotives and open carriages. The first terminus, Farringdon Street station, was opened on 10 January 1863. The station was relocated nearby on 23 December 1865 when the line was extended to Moorgate. It was renamed Farringdon & High Holborn on 26 January 1922, then re-named as Farringdon Station on 21 April 1936.

London’s population burgeoned In the first half of the 19th century; coupled with the emergence of a commuting workforce,  the result was an unacceptably high level of traffic congestion. By 1850 there were seven railway termini located around the urban centre of London: London Bridge and Waterloo to the south, Shoreditch, and Fenchurch Street to the east, Euston and King's Cross to the north and Paddington to the west. Yet only Fenchurch Street station was located within the City of London, where some 200,000 people arrived for work each day.

In 1846, Charles Pearson, Solicitor to the City of London, proposed the construction of a central railway station for use by multiple railway companies, but, later that year, the Royal Commission investigation into Metropolitan Railway Termini banned construction of new lines, including those built underground, or stations in the built-up central area. Undaunted, with the support of the City of London he helped establish the City Terminus Company in 1852 to construct a railway from Farringdon to King's Cross. The Bayswater, Paddington & Holborn Bridge Railway Company was established to connect the Great Western Railway's (GWR's) Paddington station to Pearson's route at King's Cross, appointing John Fowler as engineer.

While the company’s bid for parliamentary as the ‘˜North Metropolitan Railway‘s was successful in summer 1853, the parallel bill submitted by the City Terminus Company was rejected. The company responded quickly; it acquired the City Terminus Company and submitted a new bill in November 1853 which dropped the City terminus, extended the route south from Farringdon to terminate at the General Post Office in St. Martin's Le Grand and altered the route at the western end so that the line connected more directly to the GWR station. Permission was also sought to connect to the London and North Western Railway (LNWR) at Euston and to the Great Northern Railway (GNR) at King's Cross; the connection at King's Cross to be by hoists and lifts.

Royal Assent to the North Metropolitan Railway Act was granted on 7 August 1854, with the company now styled as Metropolitan Railway (‘˜the Met‘s). With the Crimean War imposing rising financial demands, raising the construction costs of £1 million proved very difficult and the company was forced to present new bills to Parliament seeking a longer period to carry out the works. In July 1855, an Act to make a direct connection to the GNR at King's Cross received Royal Assent. The plan was modified in 1856 by the Metropolitan (Great Northern Branch and Amendment) Act and in 1860 by the Great Northern & Metropolitan Junction Railway Act.

Despite GWR and GNR committing c. £350,000, there were still insufficient funds at the end of 1857; to cut costs, the route was pruned so that it did not connect directly to the GWR's station and dropped the route south of Farringdon. Pearson also negotiated a clever swap deal ‘“ in 1858, the Met bought land it needed around the new Farringdon Road from the City of London Corporation for £179,000, while the corporation purchased £200,000 worth of shares. Following parliamentary approval of the route changes in August 1859, the company finally had the funding to begin construction
in March 1860.

The route from Paddington to King's Cross was largely built by cut-and-cover;  eastwards, the route was constructed in a 665 m (728 yds) tunnel under Mount Pleasant, Clerkenwell then followed the culverted River Fleet beside Farringdon Road in an open cutting to the new meat market at Smithfield. Brick retaining walls were constructed In the 10.2m (33ft 6 ins) trench for the running tunnels to support an elliptical brick arch or iron girders with a 8.7 m (28 ft 6 ins) span; to accommodate platforms, the bore was wider at stations. Two three-rail mixed gauge tracks were laid to accommodate both the standard gauge trains of the GNR and the broad gauge trains of the GWR. When completed at the end of 1862, the total cost had risen to £1.3 million.

The grand opening on 9 January 1863 incorporated a ceremonial run from Paddington to Farringdon station, where a sumptuous banquet was held for 600 shareholders and guests ‘“ too late for Charles Pearson, who died in September 1862. The 6 km (3.75 miles) railway opened to the public the next day, with the GWR’s Metropolitan Class steam locomotives hauling broad gauge rolling stock provided by the GWR; trains stopped at Paddington (Bishops Road) (now Paddington), Edgware Road, Baker Street, Portland Road (now Great Portland Street), Gower Street (now Euston Square), King's Cross (now King's Cross St. Pancras) and Farringdon Street (now Farringdon). Following a disagreement between the two companies over service frequency, the GWR withdrew its stock in August 1863; the Met was forced to operate a reduced service, using standard gauge GNR rolling stock until its own standard gauge rolling stock and locomotives were produced.

The polluted atmosphere in the tunnels became increasingly unpopular with passengers. In 1904, the Met opened a 10.5 MW coal-fired power station at Neasden, with five substations supplying 600 V DC to a track level conductor rail system. Electric multiple units began running on 1 January 1905. Today, Farringdon station serves national rail along with Hammersmith & City lines, Circle Lines and Metropolitan lines. It is located between Barbican Tube station and Kings Cross Tube Station. It is the only National Rail station owned by London Underground. The station accounts for some 60 million commuter journeys a month.

The station building is an unusually well-preserved piece of early 20th-century London Underground architecture. The original signage is extant, showing "Farringdon & High Holborn" on the fa§ade, as well as other indications of the Metropolitan Railway's original main-line style operation. A sign for a "Parcel Office" survives on the exterior wall. The building is Listed Grade II.

Farringdon Station will become an important interchange between Thameslink and Crossrail lines when they open in 2018 and one of Britain's busiest stations, measured by the number of trains passing through. A new ticket hall, measuring some 165 sq m (1,776 sq. ft), was opened in 2012.