Climate change represents one of humanity?s most profound and uncertain challenges?demanding innovation, cooperation, and systemic transformation. Decarbonization Policy Engineering: Energy Transition and Regional Cooperation in East Asia provides a comprehensive, interdisciplinary framework for navigating this transition. Structured around three core themes: 1.      Strategies and Prospects for Carbon Neutrality in East Asia: This section analyzes decarbonization pathways, policy frameworks, and challenges specific to China, Japan, and South Korea. It explores national strategies, energy security, climate policy philosophy, and the potential for regional cooperation, including a joint carbon market. 2.      System Evaluation of the Optimal Energy Mix: The focus here is on the technical and engineering aspects of the energy transition. Research includes optimizing integrated energy system design, conducting scenario analyses for future pathways, and evaluating the impacts of climate change on energy consumption. 3.      Innovations for a Decarbonized Society: This segment broadens the scope to cross-cutting enablers of decarbonization. It covers climate finance, carbon accounting, technological breakthroughs, consumer behavior, carbon border mechanisms, life cycle assessment, and sector-specific strategies for waste management and residential energy use. By treating uncertainty not as a barrier but as a catalyst for innovation, this book redefines the future of energy policy. It serves as an essential compass for policymakers, researchers, and practitioners striving to engineer a sustainable, carbon-neutral future for East Asia?and beyond.