The theme of Mahdism, along with associated discourses, is a subject that has perennially stirred a keen interest in different Orientalists because of its strategic and intrinsic nature. Orientalist interaction with this theme initially introduced them to two distinct concepts: Shia Mahdism and Sunni Mahdism. Several researchers have dedicated their research to the subject of Mahdism among both Shia and Sunni populations, making a comparative and detailed analysis of this phenomenon within these two communities. The formation and clarification of the foundations of Mahdism in Shia and Sunni theology, the clarification of similarities and differences, and the role comparison analysis are salient issues that are widely seen in the works and writings of Orientalists. In the present study, the examination of Orientalist texts focuses mainly on expressing their views regarding the comparison of the origins of the Mahdist idea as understood by the two sects. This study takes into account two main theories pertaining to this topic—namely, the independence of both sects in the formation of Mahdism and the impact from Shia to Sunni—assessed based on a descriptive-analytical approach.