The article presents the result of theoretical and practical study of the relationship between state sovereignty and supranationalityof international organizations. In particular, it is determined that the phenomenon of supranationality of international organizations isderived from state sovereignty and acts as its external law. It has been shown that, in view of this, supranationality is limited becauseit arises through the exercise of sovereignty by states, and, accordingly, is limited by the amount of state sovereignty exercised by states.The relevant mechanism has also been studied on the example of the functioning of the European Union.Regarding the theoretical results, the following should be noted. First, it was proved that despite the different approaches of scho -lars to the understanding of supranationality, definitions of this concept and the separation of its features (properties), in each case,supranationality is a direct realization of state sovereignty. At the same time, the realization of state sovereignty in relation to such pro -perties of international organizations as supranational is primary, and supranationality in this case is derivative. In addition, the phenomenonof supranationality of international organizations due to the fact that it is derived is limited, because supranationality arisesthrough the exercise of sovereignty by states, and, accordingly, is limited by the amount of state sovereignty exercised by states. Thatis why when analyzing the relationship between the supranationality of international organizations and state sovereignty, one cannotconsider the priority of one of the two, because supranationality is in essence a manifestation of state sovereignty.Regarding the practical results, the author considers it appropriate to emphasize that both the regional international organization –the EU was studied, and, at the same time, it was proved that all theoretical provisions were reflected in practice, in particular, envisagedfunctions, goals and the tasks of the studied international organizations are limited in scope by the manifestation of sovereignty shownby states, similar to the regulations issued by organizations. Another indication that the state can exercise its sovereignty in any case isthat there is an effective and transparent procedure for leaving these organizations