Isigny-sur-Mer (French pronunciation: [iziɲi syʁ mɛʁ] ⓘ, literally Isigny on Sea) is a commune in the Calvados department and Normandy region of north-western France.

Situated in the fertile grassland region – known as the Baie des Veys – which constitutes the joint estuary of four rivers, Isigny is an important centre of the dairy industry.

The town is famous for its AOC butter and cream, as well as for the production of Mimolette, Pont-l'Évêque, Camembert, and Trésor d'Isigny cheeses, among others, made by the Isigny Sainte-Mère co-operative.

The industrialisation of milk processing began at the start of the 19th century: many factories were built, especially by the Dupont d'Isigny family, which then diversified and created the famous Isigny caramels.

Isigny played its part in the D-Day landings: Twenty small Dutch schuyts were employed by the Americans to bring stores and equipment inland from the larger cargo ships that were moored off-shore.