Saint-Ouen-sur-Seine is a commune in the northern suburbs of Paris, France, located 6.6 kilometres from the centre of Paris. It is part of the Seine-Saint-Denis department, in the Île-de-France region, and of the Métropole du Grand Paris. The commune was called Saint-Ouen until 2018, when it obtained a change of name by ministerial order.

Seine-Saint-Denis is a department of France located in the Grand Paris metropolis in the Île-de-France region. In French, it is often referred to colloquially as quatre-vingt treize or neuf trois, after its official administrative number, 93. Its prefecture is Bobigny.