Saint-Vallier-sur-Marne (, literally Saint-Vallier on Marne) is a commune in the Haute-Marne department in north-eastern France. Situated approximately 5 kilometers from the town of Langres, it lies within a meander of the Marne River, offering picturesque landscapes characteristic of the region.
Saint-Vallier-sur-Marne was fortified with a castle; however, it suffered devastation during the wars of the 15th century and was later occupied by Austrian forces in 1814.