The concepts of circular economy and sustainable development are recognized as the biggest challenges of today. Under such conditions, the issue of expanding the focus of the circular economy to the micro level, encouraging enterprises to transition from a linear model of the economy to circular (circular) one in conditions of economic uncertainty, is becoming actualized. Thus, the development of the theoretical basis of the concept of the circular economy of the enterprise and the formation of the definition «circular sustainability of the enterprise» as an indicator of the evaluation of the efficiency of recycling technologies. To solve the set goal, the main criteria of the circular economy were revealed in the course of the study, the differences between the circular sustainability of the enterprise, the circularity of the enterprise and the circular economy of the enterprise were characterized, the concept of the circular sustainability of the enterprise was developed, and the relationship of economic theories underlying the concept of circular sustainability was characterized enterprises. For greater thoroughness, the author investigated the following close categories: «circular economy of the enterprise», «circularity of the enterprise» and proposed a new category «circular sustainability of the enterprise». It is justified that these concepts are closely related, but not identical. The similarity between the categories is that they all aim to optimize the use of resources, reduce waste and increase efficiency in terms of environmental sustainability. The differences between the studied categories are determined by the level of application and concentration on specific aspects of management and strategy. It is substantiated that the «circular economy of the enterprise» focuses more on internal processes, the «circularity of the enterprise» covers interaction with the external environment, and the «circular sustainability of the enterprise» focuses on the long-term perspective and the inclusion of circular practices in the overall sustainability strategy. The theoretical basis of the circular sustainability of the enterprise as a symbiosis of economic theories was studied: systems theory, supply chain theory, product life cycle concepts, sustainability theory, closed loop economy theory, social responsibility theory, and innovation theory. Based on the results of the research, the author's concept of «circular sustainability of the enterprise» was developed