As a result of Russia’s full-scale invasion of Ukraine, the Ukrainian energy sector has suffered losses of $56.5 billion as of 2024. In Ukraine, there is significant potential for integrating renewable energy sources into the energy system to ensure energy security and reduce dependence on fossil fuel imports. This study was conducted to analyze Ukraine’s renewable energy market in the conditions of war and the transition to decarbonization. The impact of internal reforms and external factors on the country’s energy system was considered. The results show insufficient energy infrastructure, financial instability in Ukraine, and the need to attract investments, which should be solved by integrating renewable energy sources. The proposed algorithm for implementing the energy system development plan of Ukraine systematizes the main components of the energy system development and provides a comprehensive approach to achieving energy sustainability. This comprehensive approach could help stakeholders and policymakers regarding the renewable energy market development and management of the energy system in Ukraine.