Marly-le-Roi (French pronunciation: [maʁli lə ʁwa] ⓘ) is a commune in the Yvelines department in the administrative region of Île-de-France, France.

Marly-le-Roi was the location of the Château de Marly, the famous leisure residence of the Sun King Louis XIV which was destroyed after the French Revolution.

The Marly-le-Roi National Estate and Park now occupies much of the grounds of the former château, including restored waterways and lawns.

The inhabitants are called Marlychois or less commonly Marlésiens.

Marly-le-Roi is served by Marly-le-Roi station on the Transilien Paris-Saint-Lazare suburban rail line.