Aim. The article aims to investigate the essential and content characteristics of unitarism as a phenomenon of contemporary constitutional law. The synergistic connection between the doctrine of modern unitarism, the principles of unitarity of the state territory and the fundamental institutions of political-legal and state-administrative life of modern unitary states is shown. It proves that the unitary system is not only one of the important components of the process of accomplishing the tasks, goals and functions of most modern states, but also an immanent feature and strategic element of the mechanism of exercising their sovereign rights.
 Methods. The methodological basis encompasses philosophico-ideological, general scientific principles and approaches and special scientific methods of inquiry for constitutional and legal phenomena and processes. The philosophico-ideological basis of the study is the position of dialectics, on the basis of which the causes and factors of the evolution of unitarism are thoroughly investigated. In general, the research was conducted on the basis of a combination of ontological, epistemological and axiological analysis of contemporary unitarism.
 Results. The complexity, importance and relatively widespread use of unitarity as a form of government is causing a lively and ever-growing scientific interest in it throughout the world. The unique capability of unitarism to take into account the specific features of a particular condition allows it to manifest itself in each case in a new way. That is why it is important to analyze the mutual influence of unitary theory and practice, to explore and take into account the peculiarities of national unitarism.
 The problem of unitarism and the unitary form of the territorial structure of the state and the status of its constituents is one of the least studied in domestic constitutional law. Modern scholars studying constitutional law, as a rule, are limited to consideration of individual issues of the territory, in particular, the features of the territorial organization of state power and local self-government, problems of state sovereignty, territorial integrity and inviolability, etc. To a large extent, the problem has not been studied exhaustively in contemporary Ukraine which causes difficulties in understanding such interrelated but not identical phenomena as unitarism and unitarity, regionalism and regionalization, municipalism and municipalization, decentralization and deconcentration, etc. It should be noted that in modern literature related to problems of state territory, territorial organization of state power, and other issues of the status of territory, the complex, multidimensional nature of unitarism, as a constitutional category, is not always taken into account.
 Conclusions. Unitarism is proved to be a multidimensional socio-political and constitutional phenomenon: it is an idea, a theory, a scientific direction as well as a global social constitutional practice and a constitutional form of the existence and functioning of territorial communities, it is the historical condition of national statehood and Ukrainian regional civilization and the form of realization of the national identity and civic consciousness, etc.