Blankenburg Castle (German: Schloss Blankenburg) is a castle and administrative center in the municipality of Zweisimmen in the canton of Bern in Switzerland .

Almost nothing is known about who built the castle or when it was originally built. It first appears in the historical record in 1329 in the possession of the Freiherren von Weissenburg. It was then acquired by the Lords of Tüdingen (Duedingen) and in 1356 became the center of their Herrschaft of Mannenberg-Laubegg. In 1378 the Lord of Düdingen sold the lands and castles to Fribourg following an uprising. After the Battle of Sempach in 1386, Bern conquered the Simmen river valley (Simmental) and acquired Zweisimmen.