Pentwyn (Welsh pronunciation: [pɛnˈtʊi̯n]) is a district, community and electoral ward in the east of Cardiff, Wales, located northeast of the city centre.

Llanedeyrn is immediately to the south, Cyncoed to the west, Pontprennau to the north and the Rhymney River forms the eastern border.

[2] Pentwyn Retail Park, situated off the A48 junction near the district, hosts several other stores and food outlets.

[8] Pentwyn Leisure Centre is one of Cardiff's largest; it has a swimming pool with a wave machine, squash courts, multi-activity sports hall, fitness suite, lounge bar and cafeteria.

It is bounded by the wards of Pontprennau & Old St. Mellons to the north; Llanrumney to the east; Penylan to the south; and Cyncoed to the west.