In recent decades, “statebuilding” policies in the Greater Middle East have been used by Washington as a tool for forging an “American empire” based on unequal relations between the U.S. and its dependent regimes in Afghanistan and Iraq. At the same time, current research focuses mainly on the instruments for implementing these policies and ensuring the acceptance of new political and economic institutions by the local population. Unlike the established approaches, the author examines Washington’s statebuilding efforts as a specific practice of legitimacy aimed at entrenching sovereign inequality and institutionalizing the US political control over “client-regimes.” The study draws on the theoretical legacy of the English school, which views “legitimacy” as a phenomenon inextricably linked with “international society,” comprising a group of states bound by common goals, institutions, and values. The legitimation strategies adopted by members of this society involve the performance of various international roles through which states acquire recognized statuses, rights and obligations. Focusing on the US roles such as “imperial power” and “patron,” the author concludes that Washington’s statebuilding efforts were aimed at linking the US interventionism in Afghanistan and Iraq with the collective goals of international society, and thus served to legitimize inequitable relations with “client-states” under the formal legal equality of members of international society. Therefore, the application of the proposed approach helps to shed light on the underexplored aspects of the legitimizing instruments of the US dominance and the means of institutionalizing sovereign inequality inherent in the “American empire” in the 21st century.