It borders the Irish Sea to the north, Flintshire to the east, Wrexham to the southeast, Powys to the south, and Gwynedd and Conwy to the west.

The geography of Denbighshire is defined by the broad valley of the River Clwyd, which is surrounded by rolling hills on all sides except the north, where it reaches the coast.

This part of Wales contains the country's oldest known evidence of habitation – Pontnewydd (Bontnewydd-Llanelwy) Palaeolithic site has Neanderthal remains of some 225,000 years ago.

The county is also home to several medieval castles, including Castell Dinas Brân, Denbigh, and Rhuddlan, as well as St Asaph Cathedral.

The last includes the former Edeyrnion Rural District, part of the administrative county of Merionethshire before 1974, covering the parishes of Betws Gwerfil Goch, Corwen, Gwyddelwern, Llangar, Llandrillo yn Edeirnion and Llansanffraid.

Post-1996 Powys includes the historically Denbighshire parishes of Llanrhaeadr-ym-Mochnant, Llansilin and Llangedwyn, which formed part of Glyndŵr district.

They revealed scrapers, microliths, flakes of chert (a hard, fine-grained, sedimentary rock composed of microcrystalline or cryptocrystalline quartz), flints and other rudimentary tools.

An expert, Richard Cooke, believes the lithic remains belonged to ancient peoples, who while passing through the area, made camp by the river more than 9,000 years ago.

The uplands support sheep and beef cattle rearing, while in the Vale of Clwyd dairy farming and wheat and barley crops predominate.

Trains leaving Crewe to pass through Chester, cross the River Dee into Wales, and continue through Flint, Shotton, Holywell Junction (closed in 1966), Prestatyn, Rhyl, and stations to Bangor and Holyhead, which has a ferry service to Ireland.

The A55 dual carriageway runs from Chester through St Asaph to the North Wales coast at Abergele, then parallel to the railway through Conwy and Bangor to Holyhead.

Several services by Arriva Buses Wales run along the main coast road between Chester and Holyhead, linking the coastal resorts.

[26] Denbighshire is also represented in the Senedd by three members elected in 2021: In 2019, research by UnHerd in association with the pollster FocalData showed that most people across the county support the British monarchy.