Waasmunster () is a municipality located in the Flemish province of East Flanders, in Belgium. The municipality only comprises the town of Waasmunster proper. In 2021, Waasmunster had a total population of 10,912. The total area is 31.93 km<sup>2</sup>.
Roosenberg Abbey, founded in the 13th century, is situated here.
Illusionist Louis Courtois, writer Cyriel Geerinck, football manager and scout Urbain Haesaert and DJ/music producer Eptic were born in Waasmunster.