Val-d'Oise is a department in the Île-de-France region, Northern France. It was created in 1968 following the split of the Seine-et-Oise department. In 2019, Val-d'Oise had a population of 1,249,674.

The Île-de-France is the most populous of the eighteen regions of France, with an official estimated population of 12,271,794 residents on 1 January 2023. Centred on the capital Paris, it is located in the north-central part of the country and often called the Paris Region. Île-de-France is densely populated and retains a prime economic position on the national stage, but it covers only 12,012 square kilometres, about 2% of metropolitan French territory. Its 2017 population was nearly one-fifth of the national total.