Saxe-Weissenfels was a duchy of the Holy Roman Empire from 1656/7 until 1746 with its residence at Weißenfels. Ruled by a cadet branch of the Albertine House of Wettin, the duchy passed to the Electorate of Saxony upon the extinction of the line.

Weißenfels is the largest town of the Burgenlandkreis district, in southern Saxony-Anhalt, central Germany. It is situated on the river Saale, approximately 30 km (20 mi) south of Halle.