Named after Clapham, whose name may mean the homestead near a hill.
The Old English name, first recorded as Cloppaham around 880, may instead recall a landowner called something like Cloppa. The station stands at the corner of Balham Hill and Nightingale Lane, on the southern edge of Clapham Common. Before it opened on 13 September 1926, 'Balham North' and 'Nightingale Lane' were also proposed as names.