Postmasburg is a town in the Northern Cape province of South Africa, located approximately 170 km east of Upington.

Town 67 km (42 mi) north of Griquatown and 58 km (36 mi) west-south-west of Daniëlskuil. Originally a station of the London Missionary Society called Sibiling, it became a Griqua village with the name Blinkklip. It was proclaimed a town on 6 June 1892 and named after the Reverend Dirk Postma (1818-1890), founder of the Reformed Church.