The Principality of Aschaffenburg (German: Fürstentum Aschaffenburg) was a principality of the Holy Roman Empire created in 1803 and, following the dissolution of the Empire in 1806, of the Confederation of the Rhine, which existed from 1806 to 1810. Its capital was Aschaffenburg.
With the secularization of the Archbishopric of Mainz in 1803, Karl Theodor Anton Maria von Dalberg was compensated by receiving the newly created principalities of Aschaffenburg and Regensburg and the County of Wetzlar. Along with the city of Aschaffenburg, the Principality of Aschaffenburg also consisted of Klingenberg, Lohr, Aufenau, Stadtprozelten, Orb, and Aura.