Saint-Damase-de-L'Islet (French pronunciation: [sɛ̃ damaz də lilɛ]) is a municipality in Quebec, Canada, with a population of about 600 people nestled in the Appalachian Mountains.

It is located about 15 kilometres (9.3 mi) southeast of Saint-Jean-Port-Joli.

It is named after the Pope Damasus I and Damase Ouellet (1826–1908), which is known as the pioneer of the town.

Saint-Damase-de-L'Islet is located near the south shore of the upper Estuary of St. Lawrence, in the Côte-du-Sud region, at the eastern border of the municipalities of Saint-Aubert and Saint-Cyrille-de-Lessard.

The municipality of L'Islet, to the west, is located nearby.