Les Essarts-le-Roi (French pronunciation: [lez‿esaʁ lə ʁwa] ⓘ) is a commune in the Yvelines department in the Île-de-France in north-central France.

Les Essarts-le-Roi is bordered by Coignières and Lévis-Saint-Nom to the northeast, Dampierre-en-Yvelines to the east, Senlisse to the southeast, Auffargis to the south, Le Perray-en-Yvelines to the southwest, Les Bréviaires to the west and Saint-Rémy-l'Honoré to the north.

In 1944, the young Paris-born boy Eddy Palacci received French Resistance radio transmissions for three Allied officers, so they could receive their instructions on when and where to sabotage French railway against Nazi occupying forces.

[3] Since the 1980s, Les Essarts-le-Roi has been home to a large number of Vietnamese, who mostly arrived in France following the Vietnam War.

While refugees initially settled in Paris, the suburbanization and growing affluence of the population resulted in many moving to outer communes of the Île-de-France region.