Klosterneuburg Abbey (German: Stift Klosterneuburg) is a twelfth-century Augustinian monastery of the Catholic Church located in the town of Klosterneuburg in Lower Austria.

Overlooking the Danube, just north of the present Vienna city limits at the Leopoldsberg, the monastery was founded in 1114 by Saint Leopold III of Babenberg, the patron saint of Austria, and his second wife Agnes of Germany.