The Principality of Aschaffenburg () was a principality of the Holy Roman Empire and the Confederation of the Rhine from 1803–10. 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.