Winzenburg is a municipality in the district of Hildesheim in Lower Saxony, Germany. It comprises four smaller communities, including the village of Winzenburg, which dates from the Middle Ages. Winzenburg is located in the Leinebergland to the north of Bad Gandersheim, between the national parks of the Harz and the Weserbergland, in Lower Saxony, Germany. The municipality (German: Gemeinde) was formed in March 1, 1974 from the four previously independent communities of Winzenburg, Schildhorst, Westerberg and Klump and forms part of the Samtgemeinde of Freden. It is near the small town of Freden.
Winzenburg is chiefly known for Winzenburg castle, a medieval castle now in ruins, which stands on a spur of the Sackwald. In the vicinity, it is also known for its man-made fishing ponds where one can either fish at one of the five ponds or eat fish at one of the Fischerhütte, the small nearby restaurants. Count Hermann II of Winzenburg built the castle at Schöneberg.