Ommerstein Castle (Dutch: Kasteel van Ommerstein) is a castle in the village of Rotem in the municipality of Dilsen-Stokkem, province of Limburg, Belgium.

The history of the castle goes back to the 13th century, but most of the present Neo-classical building dates from the 18th century, although the donjon survives from earlier.

The surrounding park is distinguished by its possession of a number of giant sequoias and cedars of Lebanon, including one believed to be the thickest in Belgium. There are also several ponds round the castle.

• List of castles in Belgium

51°02′46″N 5°44′31″E / 51.046°N 5.742°E / 51.046; 5.742