Pénestin (French pronunciation: [penetɛ̃];[3][4][5] Breton: Pennestin) is a commune in the Morbihan department of Brittany in north-western France.

The mouth of the river Vilaine forms a natural bourndary to the north.

As Penestin lies on the coast, it boasts several beaches, the most popular of which are La Mine d'Or and Loscolo.

Until the beginning of the nineteen's century, the spoken language was breton.

As of 2020, 71.1% of the properties are holiday homes,[8] one of the highest percentage in Morbihan.