Saint-Ouen-l'Aumône (French pronunciation: [sɛ̃t‿wɛ̃ lomon] ⓘ) is a commune in the northwestern suburbs of Paris, France.

It is located 27.6 km (17.1 mi) from the center of Paris, in the "new town" of Cergy-Pontoise, created in the 1960s.

Saint-Ouen-l'Aumône is served by two interchange stations on Paris RER C line and on the Transilien Paris-Nord suburban rail line: Saint-Ouen-l'Aumône-Liesse and Saint-Ouen-l'Aumône.

Saint-Ouen-l'Aumône is also served by two other stations on the Transilien Paris-Nord suburban rail line: Épluches and Pont-Petit.

Finally, Saint-Ouen-l'Aumône is also served by Saint-Ouen-l'Aumône-Quartier de l'Église station on the Transilien Paris-Saint-Lazare suburban rail line.