In theological writings and well-known and common treatises on sects and religions, the title “Khorramiyya” has been repeated many times, and it is considered one of the deviant sects among Muslims. Subsequently, many contradictory and opposing claims have been made about it. How the title Khorramiyya was formed in the second and third centuries AH and their religious beliefs remain among the ambiguous and sometimes mysterious issues in sect studies. Therefore, this article attempts to use the library method and examine historical books and theological and sect-writing texts, in addition to removing the ambiguity of the ideological currents titled “Khorramiyya,” to provide a clear and transparent picture of the beliefs of the followers of these currents. The result was that throughout history, the title “Khorramiyya” was applied to three separate ideological-military currents that emerged in the regions of Khorasan and Transoxiana, Ray and Jabal, as well as Azerbaijan, and the common axis of this naming and application of this title was only their commonality in opposing and fighting the Abbasid Caliphate.