Anticosti Island (French, l'Île d'Anticosti) is an island at the outlet of the Saint Lawrence River into the Gulf of Saint Lawrence, in Quebec, Canada.

It is separated on the north from the Côte-Nord region of Quebec (the Labrador Peninsula) by the Jacques Cartier Strait and on the south from the Gaspé Peninsula by the Honguedo Strait.

It is very large (217 km long and 16-48 km wide - larger than the province of Prince Edward Island), but very sparsely populated (264 people in 1991), mostly in the village of Port-Menier on the western tip of the island.

It was discovered by Jacques Cartier in 1534, and was granted to Louis Joliet by Louis XIV as a reward for discovering the Mississippi River. It stayed in Joliet's family until 1763, when it was annexed by the colony of Newfoundland. Canada regained it in 1774. It supported timber harvests until 1972, and is now an important site for deer hunting.