Oudebildtzijl (West Frisian: Aldebiltsyl; Bildts: Ouwe-Syl) is a village in Waadhoeke municipality in the province of Friesland, the Netherlands. It had a population of around 690 in January 2017. It is the starting point from which the Oude Bildtdijk was created. Until 2018, the village was part of the het Bildt municipality.