Waldemar III, Prince of Anhalt-Zerbst (died 1391) was a German prince of the House of Ascania and ruler of the principality of Anhalt-Zerbst.
He was the youngest son of John II, Prince of Anhalt-Zerbst, by his wife Elisabeth, daughter of John I, Count of Henneberg-Schleusingen.
Waldemar inherited the principality of Anhalt-Zerbst when his father died in 1382.
According to the family law of the House of Ascania, he was obliged to rule jointly with his older brothers Sigismund I and Albert IV.
This article related to German royalty (1871–1919) is a stub.