Penrhyn Bay (Welsh: Bae Penrhyn) is a small town on the north Wales coast, in Conwy county borough, within the parish or community of Llandudno, and part of the ecclesiastical parish of Llanrhos. It is a prosperous village with a cluster of local shops, a pub, a parish church and a modern medical centre with doctors' surgery at the foot of the pass over the shoulder of the Little Orme from Llandudno Bay. It is considered to be a residential suburb of Llandudno lying east of the Little Orme. It adjoins the resort of Rhos-on-Sea.

The oldest building in Penrhyn Bay is Penrhyn Old Hall dating from the early 15th century. It was the home of the Pugh family whose fortunes faded through their adherence to the Catholic religion when their neighbours reluctantly accepted Protestantism. On 14 April 1587, printing material for Catholic literature was found in a cave on the Little Orme, where it had been used by the recusant Robert Pugh (squire of Penrhyn Hall) and his chaplain William Davies to print Y Drych Gristianogawl ('The Christian Mirror'). They had taken refuge there during the persecution of Catholics instigated by Queen Elizabeth I in May 1586. In the grounds of the hall are the ruins of the medieval chapel of the Blessed Virgin Mary of Penrhyn, last used by the Church in Wales for public worship c1930. The Pugh family also held a charter and built a windmill to serve their land in the near by village of Glanwydden the first charter dating 1580. The hall now serves as a pub and restaurant.

Originally a small farming community, Penrhyn Bay came to rely heavily on the employment opportunities of the limestone quarry operating since the mid 1800s, and served by its own narrow gauge railway, but quarrying ceased in 1936. However, Penrhyn Bay expanded rapidly in the 20th century to become a desirable suburb of Llandudno, with developments taking place in the 1930s, 1950s and 1960s. Most recently, in the 1990s, further large development of family homes took place to the south of the town.

Celebrity connections
Penrhyn Bay was the location for an episode of TV's Hetty Wainthropp Investigates television series, which starred Patricia Routledge.

Magician Emma Rostron, who aided Paul Daniels before he met Debbie McGee, lives on the Beach Estate.