Oostvoorne is a town in the Dutch province of South Holland. It is a part of the municipality of Westvoorne, and lies about 9 km north of Hellevoetsluis.
In 2001, the town of Oostvoorne had 5,403 inhabitants, the built-up area of the town was 1.9 km², and contained 2,274 residences.
The statistical area "Oostvoorne", which also can include the peripheral parts of the village, as well as the surrounding countryside, has a population of around 7,270.
Oostvoorne was a separate municipality until 1980, when it became part of Westvoorne.
Oostvoorne was since before World War II the only location in the Netherlands where automobiles were permitted on the beach. In 1992 it was proposed to close the beach to cars resulting in consultations and negotiations lasting many years. The provincial government finally decided to close it permanently on October 15, 2004.
In the centre of Oostvoorne are the ruins of a motte-and-bailey castle, built around the second half of the 12th century by the Lords of Voorne, which also served as a residence for Jacqueline, Countess of Hainaut.