Sundern (German pronunciation: [ˈzʊndɐn] ⓘ) is a town in the Hochsauerland district, in North Rhine-Westphalia, Germany.

The name Sundern is common in Westphalia, as it means "ground given away for private usage" in the Westphalian dialect.

Sundern is situated approximately 10 km (6 mi) south-west of Arnsberg.

Around Sundern extends the nature park Homert which attracts tourists, many from the Netherlands.

Winter tourism is also substantial, primarily in the municipality Wildewiese with its skiing area.