Oudenburg (Dutch pronunciation: [ˈʌudə(m)ˌbʏr(ə)x]; French: Audembourg [odɑ̃buʁ]; West Flemish: Oednburg [ˈʊdn̩bœrh]; Latin: Aldenburgensis) is a city and municipality located in the Belgian province of West Flanders.

The municipality comprises the city of Oudenburg itself and the towns of Ettelgem, Roksem and Westkerke.

Oudenburg is situated on the location of a Roman castellum built in the 4th century, whose outline is still visible in the city's streetplan.

The former abbey of St. Peter at Oudenburg, founded by Arnold of Soissons, was destroyed during the French Revolution.

The castle already appeared on the oldest seal of the city, dating from 1226.