The County of Rietberg was a state of the Holy Roman Empire, located in the present-day German state of North Rhine-Westphalia. It was situated on the upper Ems in Westphalia, between the Prince-Bishopric of Paderborn and the Prince-Bishopric of Münster. It existed as an independent territory from 1237 to 1807, when it was mediatised to the Kingdom of Westphalia.