The research aims to identify the main problems and areas of cooperation between the countries of the Eurasian Economic Unity (EAEU) in the energy sector. The countries decided to form a single energy market of the EAEU, which will solve the problem of ensuring the energy security of the member countries. As a basis for studying cooperation, the fuel and energy complex is considered a complex and diversified system that includes a full cycle of energy production: from its extraction to delivery to consumers. Based on open information sources, the main problems hindering the formation of a single energy market, as well as the possibility of completing this process in the near future, are formulated. The authors established that the EAEU countries have similar problems, such as outdated infrastructure and production assets in the face of increasing needs of the domestic market, insufficiently high energy efficiency of the economy, organizational and technical difficulties associated with the development and implementation of new equipment and technologies, and insufficient investments. The internal energy markets of the EAEU countries remain fragmented. There is no unified investment space. The rules and principles of state regulation in the energy sector have numerous differences. The EAEU countries do not sufficiently use the benefits of conducting cross-border cooperation in the energy sector and entering foreign markets by uniting. To build a single energy market, the main task of the EAEU countries is to concentrate efforts on the efficient use of energy potential for further integration. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023.