Modern socio-economic development of regions is impossible without ensuring a stable state of the energy complex of the territory, directly related to its energy efficiency. Reducing energy intensity, increasing energy efficiency is a key area for achieving sustainable growth of the country’s economy in conditions of non-stationarity. Reforms related to the regulation of tariffs, the development of subsidies and the rollback of cross subsidization, the delineation of social and energy policies are extremely slow in the face of the need for large investment for the aging infrastructure of the energy complex. The most difficult situation is in the regions where the main part of the territories is provided with electric and thermal power due to the operation of isolated energy systems. In most regions of the Far East, power systems operate in both territorial (Sakhalin, Kamchatka) and in landscape (Magadan Region, Chukotka Autonomous District). The reliability of the energy supply of these territories is more tied to the technological aspects of energy supply and energy security. With a large area of the territories of most regions of the Far East and the associated low demand for generation of thermal electricity due to the lack of large and medium industrial consumers and a small population, the problem of unprofitable connection to the centralized power supply of remote small settlements arises. As a result, there is a need to assess the nature of the relationship between energy efficiency and socio-economic development of the territory. In this regard, the authors propose to consider the state of sustainability of energy systems in conditions of increasing their energy efficiency from the point of view of 7 complex indices reflecting social, economic (including technological), environmental and management aspects of development. In the article, based on the author’s approach, the impact on the socio-economic development of the regions of the Far East of the dynamics of the sustainability of energy systems in the context of the situation in the field of increasing their energy efficiency is analyzed.