The war in Ukraine has had profound implications for global energy markets, with particularly significant effects on Greece’s energy sector. This dissertation examines the impact of the conflict on Greece’s energy security, supply diversification efforts, economic stability, and long-term policy shifts. Through an analysis of energy supply disruptions, price volatility, and infrastructure developments, the study highlights Greece’s strategic responses, including increased LNG imports, accelerated renewable energy projects, and regional cooperation initiatives. The research findings suggest that while Greece has faced substantial economic and social challenges due to rising energy costs, the crisis has also accelerated necessary transitions towards greater energy security and sustainability. Policy implications underscore the need for enhanced energy diversification, infrastructure investments, and technological advancements in renewable energy and storage solutions. Furthermore, Greece’s evolving role as a regional energy hub within Southeastern Europe is examined in the context of broader geopolitical and economic transformations. This study contributes to the understanding of how external geopolitical crises influence national energy policies and offers recommendations for future research on Greece’s energy transition, technological innovations, and regional energy cooperation. Ultimately, the findings highlight the resilience and adaptability of Greece’s energy sector in navigating global energy challenges.