Saint-Thurien (French pronunciation: [sɛ̃ tyʁjɛ̃]; Breton: Sant-Turian) is a commune in the Finistère department of Brittany in north-western France.

Saint-Thurien is border by Guiscriff to the north, by Querrien to the east, by Mellac to the south and by Bannalec to the west.

The parish church was rebuilt at the end of the nineteenth century in accordance with the architect Joseph Bigot's plans.

The Peny factory, located on the banks of the river Isole, with 340 employees, in the main employer in the town.

Since 1995, it is twinned with the village of Kilmacow in County Kilkenny, Ireland .