[3] The communes neighbouring Saint-Ouen-sur-Seine are Paris, to the south, Clichy, to the west, Villeneuve-la-Garenne, Gennevilliers and L'Île-Saint-Denis, to the north, and Saint-Denis to the east.

At the same time, the commune of La Chapelle-Saint-Denis was disbanded and divided between the city of Paris, Saint-Ouen, Saint-Denis, and Aubervilliers.

In 2014 the flea market site was acquired by Jean-Cyrille Boutmy from Gerald Grosvenor, 6th Duke of Westminster.

Saint-Ouen-sur-Seine has: Supméca, an accredited mechanical engineering school is located in the Vieux Saint Ouen quarter.

One literary and humanities Classe préparatoire aux grandes écoles is offered on the Lycée Blanqui high school's premises.