Mornay-sur-Allier (French pronunciation: [mɔʁnɛ syʁ alje]) is a commune in the Cher department in the Centre-Val de Loire region of France.

An area of lakes and streams, forestry and farming comprising the village and several hamlets situated by the banks of the river Allier, some 33 miles (53 km) southeast of Bourges, at the junction of the D45 and the D2076 roads.

The commune borders the departments of Allier and Nièvre.