Tremeirchion is situated in the county of Denbighshire, North Wales. It is bordered by Rhuallt to the north, Bodfari to the south, St Asaph to the north west and the Clwydian mountain range to the east. Nearby towns and villages include Trefnant, Caerwys, Holywell, Rhuddlan, Prestatyn, Bodelwyddan and Denbigh.

Tremeirchion is close to the Clwydian Way, a walking route which covers 122 miles from Prestatyn through to Llangollen, Denbigh, Rhuddlan and Ruthin. Also to the north of the village lies part of the Offa's Dyke path, a 177 mile long walking trail from Prestatyn to Chepstow. Both walks offer incredible views of the Clwydian mountains, taking in beautiful rural countryside and peaceful towns and villages.

Tremeirchion is also home to St Beuno's College, a Jesuit college at which the Victorian era poet and Jesuit priest Gerard Manley Hopkins studied. It now runs spiritual retreats of varying durations.