Modern Iran has experienced three major forms of political order: the Constitutional state, the Pahlavi authoritarian state, and the Islamic Republic. This study examines the formulation of the concept of the nation and national sovereignty during the formation of the Islamic Republic, with particular emphasis on the political thought of Ayatollah Seyyed Mohammad Hosseini Beheshti. As one of the principal architects of the Islamic Republic and a key figure in drafting the 1979 Constitution, Beheshti sought to reconcile republicanism with Islam while defining the political role of the nation within the framework of the Ummah and Imamate system. The study asks how Beheshti conceptualized the nation, whether the Islamic Republic can be understood as a national state in his thought, and how he distinguished the national question from the religious question. The findings indicate that, despite his criticism of nationalism as an ideological doctrine, Beheshti recognized the nation and national sovereignty as legitimate political categories and acknowledged the nation’s role in determining the political order and selecting political leadership. However, he did not regard national sovereignty as an autonomous and unrestricted source of political legitimacy. Although he distinguished between the national and religious domains, he did not develop a fully systematic relationship between the concepts of nation and Ummah. Consequently, the nation occupies an intermediate position between the modern territorial nation and the religiously defined Ummah in Beheshti’s political thought.