Bryncethin is situated near Sarn in Bridgend county, south Wales. It is bordered by Abergarw to the north, Bryncoch to the south, Tondu to the west and Heol-y-Cyw to the east.

Nearby towns and villages include Bridgend, Tondu, Aberkenfig, Pencoed, Llangeinor, Bettws, Pyle, Laleston, Coychurch, Heol y Cyw, Hendreforgan, Lewistown and Coychurch. The Ogwr Fawr river passes 0.5km north west of Bryncethin.

Those with a passion for shopping will be pleased to know that there is a popular Designer Outlet at Bridgend, 3 miles south of Bryncethin. It is home to such design brands as Calvin Klein, Gap, Nike, Karen Millen, Next, French Connection, Bench, Jaeger, Ted Baker, Clarks, Vans and Reebok, and food outlets including Pizza Hut, Upper Crust and Spud U Like. There is an interesting burnt mound around 1.5km south east of the village, near the M4 motorway.