Plœuc-sur-Lié (French pronunciation: [plœk syʁ lje]; Breton: Ploheg) is a former commune in the Côtes-d'Armor department in Brittany in northwestern France.

The average annual rainfall is 929.8 mm (36.61 in) with December as the wettest month.

In 1643, as a reward for services rendered at the siege of La Rochelle (1627-1628), King Louis XIV granted Sebastian de Ploeuc the right to hold four fairs a year and also a weekly market.

The Count de La Rivière was the ancestor of Lafayette, who sold his estates at Ploeuc to cover the expenses which fell on him as a result of the American War of Independence.

Today, Plœuc-sur-Lié retains its rural character, with a prosperous agriculture which is largely from potato growing.