The main purpose of this research is to assess the energy efficiency in Russia on its path towards the modernization of its energy systems. This modernization can be seen as an effective means for promoting decarbonization and energy-saving initiatives. Our methods include a comprehensive overview of the development of the energy sector in Russia, which is distinguished by the high concentration of state-owned enterprises, the absence of clear market mechanisms, as well as the domination of the fossil fuels represented by natural gas and oil. Furthermore, we present the perspectives of developing the renewable energy technologies in Russia. Our results enable us to create an in-depth analysis of the perspectives of modernization of the Russian energy sector and to draw the key connotations for its further development. Moreover, the outcomes of this paper can provide useful policy implications and guidelines for modernizing energy efficiency and energy systems for Russian stakeholders and policy makers, supporting their efforts to reduce the dependency on carbon fuels and to embark on the path towards the sustainable economic growth and development.