Ormesson-sur-Marne (; 'Ormesson-on-Marne') is a commune in Val-de-Marne in the southeastern suburbs of Paris, France. It is located 16.1 km (10 mi) from the centre of Paris.
Ormesson-sur-Marne is served by no station of the Paris Métro, RER, or suburban rail network. The closest stations to Ormesson-sur-Marne are two stations on Paris RER line A: Sucy – Bonneuil and La Varenne – Chennevières. The former is located in the neighboring commune of Sucy-en-Brie, from the town center of Ormesson-sur-Marne, and the latter is located in the neighboring commune of Saint-Maur-des-Fossés, from the town center of Ormesson-sur-Marne.
Schools in the commune include:
High school/sixth-form students attend Lycée Samuel de Champlain in Chennevières-sur-Marne.
As of July 2016, Ormesson-sur-Marne is twinned with Northallerton in North Yorkshire.