Abstract Ukraine's energy geography, shaped by its vast network of natural gas pipelines, extensive nuclear infrastructure, and rapidly expanding renewable energy sector, unequivocally underscores its pivotal and evolving role in European energy security. This position is particularly critical amid escalating geopolitical tensions and the continent-wide imperative for decarbonization. This study analyzes the profound implications of key developments, such as the cessation of Russian gas transit via Ukraine in January 2025, a move that significantly diminished its historical transit leverage but also accelerated its path towards energy independence. Concurrently, the nation's nuclear power plants, exemplified by the Zaporizhzhia facility, face ongoing and severe risks from military occupation and attacks, raising serious concerns about safety and regional stability. Amid these challenges, Ukraine is aggressively pursuing a green transition, with renewables aiming to constitute 27% of its energy consumption by 2030, aligning with European decarbonization goals. Drawing on comprehensive 2025 data and recent geopolitical shifts, findings reveal a decisive strategic pivot: Ukraine's move from historical gas dependency towards a model of diversified energy exports and strengthened interconnections with the European Union. While this transition enhances overall EU energy resilience and strengthens Ukraine's long-term energy security, it also exposes new vulnerabilities related to infrastructure security and economic adjustments. Recommendations emerging from this analysis advocate for urgent international collaboration to bolster grid ties, modernize existing infrastructure, and establish robust international safeguards to protect critical energy assets, thereby solidifying Ukraine's indispensable strategic position as a resilient and reliable energy partner for Europe.