Clanwilliam is a town in the Olifants River valley in the Western Cape, South Africa, about 200 kilometres (120 mi) north of Cape Town. It is located in, and the seat of, the Cederberg Local Municipality. As of 2001 Clanwilliam had a population of 6089.
Clanwilliam is situated at an elevation of 100 metres (330 ft), between the western slopes of the Cederberg mountains and the east bank of the Olifants River, which is impounded there by the Clanwilliam Dam. It is located just off the N7 national road, which runs from Cape Town to the Namibian border, and on the R364 road, which runs from Lamberts Bay to Calvinia. Clanwilliam is 230 kilometres (140 mi) from Cape Town by road.
Clanwilliam is the birth place of ZP Theart, former lead vocalist of the British power metal band DragonForce.