The Second Nagorno-Karabakh War not only altered the regional balance of power and the geopolitical configuration of the South Caucasus but also exerted significant influence on regional and extra-regional relations, regional security and stability, and political, economic, and cultural cooperation among the countries of the region. The conflict further contributed to the emergence of an unstable security environment along the northwestern borders of the Islamic Republic of Iran, accompanied by the increased involvement of regional and international actors. In light of the provisions of the ceasefire agreement imposed on Armenia, the military, security, political, and geopolitical consequences of the war have the potential to substantially affect the national interests of the Islamic Republic of Iran. Accordingly, this study examines the implications of the Second Nagorno-Karabakh War for Iran's national interests. The primary objective of the research is to identify and analyze the consequences of the 2020 Second Nagorno-Karabakh War for the national interests of the Islamic Republic of Iran. The study adopts an applied descriptive-analytical research design. Data obtained through documentary research were statistically analyzed using SPSS software, employing the one-sample t-test and Pearson correlation analysis. The findings identify three principal dimensions of the war's consequences: (1) its impact on the strategic role and regional engagement of the Islamic Republic of Iran in the Caucasus (10 indicators); (2) its influence on the activities of the Zionist regime and Russia in the Caucasus region (9 indicators); and (3) its implications for the international borders of the Islamic Republic of Iran (5 indicators). Collectively, these findings demonstrate that the Second Nagorno-Karabakh War has generated significant geopolitical and security consequences with direct implications for Iran's national interests and strategic posture in the South Caucasus