Caerphilly County Borough (Welsh: Bwrdeistref Sirol Caerffili) is a county borough in the south-east of Wales. It is governed by Caerphilly County Borough Council.
Its main and largest town is Caerphilly. Other towns in the county borough are, Risca, Ystrad Mynach, Newbridge, Blackwood, Bargoed, New Tredegar and Rhymney.