​An important figure in the Umayyad and Abbasid eras, Abū Ayyūb al-Mūryānī first entered the diwan of the Abbasid caliphate as a clerk before going on to hold a series of prestigious positions there. Al-Mūryānī rose rapidly through the ranks, and by virtue of his close association with the second Abbasid caliph, Abū Ja'far al-Manṣūr, he was elevated to the post of vizier. Yet, despite his renown and the significant contribution he made to the development of Abbasid administrative procedures, al-Mūryānī, like his Ahvazi peers and contemporaries, has remained shrouded in obscurity, with hardly a mention among the prominent personalities associated with that state. Relying on classical sources and a historical-analytical approach, this paper traces al-Mūryānī's political career, exploring the most important factors that led to his demise through a careful examination of the accounts that chronicled this event before it was officially recognized and incorporated into historical narratives.