Épinay-sur-Orge (French pronunciation: [epinɛ syʁ ɔʁʒ] ⓘ, literally Épinay on Orge) is a commune in the Essonne department in Île-de-France in northern France.

Épinay is served by two stations on different branches of line C of the RER suburban railway system: Épinay-sur-Orge and Petit-Vaux.

Traces of habitations from the Middle Ages have been found at Breuil (in the South) and Petit Vaux (West of the present-day centre).

In May 1843, the development of the town received a boost from becoming a stop on the Paris-Orléans railway, now the main RER station.

Épinay-sur-Orge was long known for its system of market gardens, providing Parisians with fresh vegetables.

The building was the expatriate home of a rich Irishman who left it to the Department of the Essonne in 1863 on the condition that it be turned into an "asylum for the mad".