The article examines the functioning of the public sector of the economy at the present stage of development and substantiates its importance for the socio-economic system of the country. The aim of the study is to study theoretical concepts about the public sector of the economy and its structural components. The question of the role and place of the public sector in the functioning of the socio-economic system is relevant. The public sector is represented as an independent, specific and complex system within the national economy. The activities of this sector of the economy are based on state ownership and are aimed at implementing the state socio-economic policy. The main structural components of the socioeconomic system of the public sector are public administration, the social sphere and state entrepreneurship. The purpose and objectives are defined, the functions of the public sector are summarized, the main types of state activities and the features of the functioning of such a sector of the economy are given. At the present stage of socio-economic development of the country, the public sector produces the goods necessary for society and provides various services, such as ensuring public security, education, health care, social protection of the population, etc. The main interrelations of the public sector with economic agents and the principles of public-private partnership are considered. State regulation of the national economy system is carried out through the structures of the public sector through the implementation of fiscal, monetary and social policies. The article substantiates the importance of the public sector in the process of creating prerequisites for sustainable economic growth in the country, improving the quality of life and increasing the level of public welfare. The importance of the public sector for the national economy is proved, since for the stability of the socio-economic system and its development, the state forms a more appropriate economic infrastructure of the country, maintains a balance of macroeconomic proportions.