Saint-Briac-sur-Mer (French pronunciation: [sɛ̃ bʁijak syʁ mɛʁ], literally Saint-Briac on Sea; Breton: Sant-Briag; Gallo: Saent-Beriac), is a commune in the Ille-et-Vilaine Department in Brittany in northwestern France.

On 4 and 5 September 1758, a British fleet of 113 ships under the command of Admiral Richard Howe, landed east of the Garde Guerin, in Saint Briac.

With a force of more than 12,000 men, under the command of General Thomas Bligh, who accompanied the Duke of York, the future king George III, they established camp in neighboring St Lunaire, but not before pillaging and burning down more than half of Saint Briac.

The current mayor is Vincent Denby Wilkes Princess Victoria Melita of Edinburgh and Saxe-Coburg-Gotha, the Titular Empress of all the Russias, lived here with her husband and their son and one of their daughters.

Kira Kirillovna of Russia, their youngest daughter and wife of Louis Ferdinand, Prince of Prussia heir to the Prussian Throne.