The Radnor district was created under the Local Government Act 1972 and replaced the following local government areas from April 1, 1974:

• The urban districts of Knighton, Llandrindod Wells and Presteigne
• The rural districts of Colwyn, Knighton, New Radnor, Painscastle and Newton and Rhayader

The district was abolished in 1996 by the Local Government (Wales) Act 1994 when it became part of the unitary authority of Powys.