Rüthen is a town in the district of Soest, in North Rhine-Westphalia, Germany.

Rüthen is situated at the northeastern border of the natural preserve Arnsberger Wald between the Haarstrang and the valley of the river Möhne, approx. 20 km south of Lippstadt and 35 kilometres (22 mi) south-west of Paderborn. The highest point is the Wehberg with a height of 528.9 metres (1,735 ft), the lowest point the valley of the river Pöppelsche at 130 metres (430 ft). With an area of more than 310 square kilometres (120 sq mi) it is the largest town within the district of Soest.