The station is in Battersea not Clapham. Before the railway came the area was rural and specialised in growing lavender; the street Lavender Hill is east of the station. The coach road from London to Guildford ran slightly south of the future station site, past The Falcon public house at the crossroads in the valley between St. John's Hill and Lavender Hill. On 21 May 1838 the London and Southampton Railway, became the London and South Western Railway (L&SWR), and opened its line from Nine Elms as far as Woking. That was the first railway through the area but it had no station at the present site. The second line, initially from Nine Elms to Richmond, opened on 27 July 1846. Nine Elms was replaced in 1848 as the terminus by Waterloo Bridge station, now Waterloo. The line to Victoria opened by 1860. Clapham Junction opened on 2 March 1863, a joint venture of the L&SWR, the London, Brighton and South Coast Railway (LB&SCR) and the West London Extension Railway (WLER) as an interchange station for their lines. When the station was built much of Battersea was treated as and cast as a heavy industry district while Clapham a mile south-east of this point was fashionable. The railway companies, to attract a middle- and upper-class clientele, claimed the station as being upon the slopes of Clapham's plateau, leading to a long-lasting misunderstanding that the station is in Clapham. The railway companies were not alone in eschewing Battersea, from the 1880s until the 1950s the imposing private houses forming the streets of the district were commonly recorded by property-owning residents as 'Clapham Common'. Whereas the station brought wealthy streets to Battersea its adjoining (entirely modernised) manual railway works and the large Battersea Power Station brought slums and the population of which rose from 6,000 in 1840 to 168,000 by 1910. Battersea's slums unfit for human habitation were entirely replaced with council and charitable housing between 1918 and 1975.
Each day about 2,000 trains, over half of them stopping, pass through the station, more than through any other station in Europe. At peak times 180 trains per hour pass through of which 117 stop. It is not the busiest station by number of passengers, most of whom (about 430,000 on a weekday, of which 135,000 are at rush hours) pass through. Interchanges make up some 40% of the activity and on that basis too it is the busiest station in the UK. In 2011, the station had three entrances, all with staffed ticket offices, though only the south-east entrance is open 24 hours a day. The most heavily used of the three, this leads from St John's Hill via a small indoor shopping centre, into a subway some 15 ft (4.6 m) wide that connects to the eastern ends of all platforms. The north entrance, which has restricted opening hours, leads from Grant Road to the same subway. The subway is crowded during rush hours, with the ticket barriers at the ends being pinch points. The south-west entrance, also known as the Brighton Yard entrance, as the buildings still bear signage for the London Brighton and South Coast Railway, is of a more traditional appearance, with a Victorian station building set at the back of a large forecourt. This entrance leads to a very wide covered footbridge, which joins the western ends of all platforms. This entrance includes cycle parking and a taxi rank. The station has 17 platforms, 1 to 17. The original platform 1 (now 0) is disused, and platform 2 has been split into two (1 and 2). Platforms 1–6, the northern group, lie in a west-southwesterly direction; platforms 7–17, the southern group, in a southwesterly direction. There are public and disabled toilets at the south-west entrance. There are refreshment kiosks in the subway, on the footbridge and on some platforms; and a small shopping centre, including a small branch of Sainsbury's supermarket, in the south-east entrance. The station is in Travelcard Zone 2 and has payphones, a waiting room, boarding ramps, cash machines, help points and toilets.
Connections: National Rail. East London Line (London Overground). London Buses routes 35, 37, 39, 49, 77, 87, 156, 170, 219, 295, 319, 337, 344, 345, 639, 670, C3 and G1 and night routes N19, N31, N35 and N87 serve the station.