The administrative county of Gwynedd was created in 1974 as part of a local government reorganisation in England and Wales. Gwynedd incorporated the counties of Anglesey and Caernarfonshire, most of Merionethshire, and a few parishes in Denbighshire. Gwynedd's social services department took over the management of children's homes previously run by the Anglesey County Council, Carnarvonshire and Merionethshire County Councils.

Following a further reorganisation in 1996, Gwynedd was abolished and its local government was divided among a number of new administrations: the Isle of Anglesey became an independent authority, and Aberconwy (which included the former Denbighshire parishes) became part of the new Conwy County Borough. The remainder of the area was reconstituted as the County of Caernarfonshire and Merionethshire, as it covers most of the areas of those two historic counties. As one of its first actions, the Council renamed itself Gwynedd on 2 April 1996.