The research relevance is predetermined by the need to study the key fundamentals of the energy security system at the international and national levels. Among the urgent issues caused by the challenges and threats of modern life, primarily due to the full-scale invasion and aggression of Russia against Ukraine, the provision of energy security, principles, legal, organisational, and other foundations, implementation mechanisms, and corresponding guarantees are singled out. The purpose of the research is to carry out a general theoretical comprehensive analysis of the principles of ensuring energy security, their typology, and justification of the need for modernisation. The research uses a complex of scientific methods: epistemological, phenomenological, statistical, modeling and forecasting, formal-legal, comparative-legal, historical-legal, etc., as well as an anthropological approach. The study comprehensively highlights the essence and features of the principles of ensuring energy security, taking into account the interdisciplinary, cross-industry nature of the process of ensuring energy security. Based on available doctrinal and regulatory legal sources, the concept and legal essence of the principles of law, and principles of ensuring energy security were analysed; the author’s vision of the criteria for the classification of the latter is substantiated, their varieties, the legislative basis of regulation and implementation, problems on this path and directions for their solution are considered. The terminological uncertainty, a certain non-systematic and inconsistency of the state energy policy of Ukraine, its organizational and legal foundations, and implementation mechanisms were noted. Therefore, the practical significance of the publication lies in the typology of the principles of ensuring energy security, the demarcation of the principles of energy policy of Ukraine, the principles of implementation of state policy in the sphere of energy security, the main fundamental principles of the strategy of cooperation in the energy sphere, etc. It is natural to modernise the existing principles of ensuring energy security, increase their efficiency, and strengthen the energy independence of the Ukrainian state, primarily in the conditions of the legal regime of martial law and post-war peacebuilding, cooperation in the field of energy and energy efficiency