Gilfach is situated south of Bargoed in Caerphilly County, South Wales. It is bordered to the south by Glan-y-nant, to the west by Taff Merthyr and to the east by Pengam, with surrounding towns and villages including Blackwood, Ystrad Mynach, Newbridge, Abercarn, Abertillery and Tredegar. The village sits on the banks of the Rhymney river, which runs through Caerphilly before joining the Severn estuary at Cardiff Bay.

Gilfach abounds with organisations and institutions, including a YMCA building, Workingmen's Club, OAP Welfare Hall and Scout Hall, as well as tennis courts and a bowling green for outdoor activities.

Formerly a coal mining colliery, the country park at nearby Bargoed is now complete with nature trails, cycle paths and lakes.