Port-Louis (French pronunciation: [pɔʁ lwi] ⓘ; Breton: Porzh-Loeiz) is a commune in the Morbihan department of Brittany in north-western France.

In 1664, during the reign of King Louis XIV, the French East India Company was established at Port-Louis.

At the time, the governor of Brittany, Philippe Emmanuel, Duke of Mercœur, a Catholic, was in revolt against the new Protestant king Henry IV, and the Spanish were invited to provide support to their coreligionists.

Henry converted to Catholicism in 1593, and eventually defeated de Mercœur in 1598, gaining control of the fort.

Today, the citadel houses four museums: Inhabitants of Port-Louis are called in French Port-Louisiens.