This chapter examines climate-induced migration’s impact on demographic change in East Asia, focusing on Mongolia as a case study. It argues that climate mobility is a structural force reshaping regional population dynamics, driven by historical patterns and intensified by contemporary climate change. Mongolia’s experience with Dzud-related migration illustrates how ecological collapse, rural decline, and urban pull factors lead to significant internal shifts, creating both opportunities and vulnerabilities. The chapter analyzes the complex demographic consequences of Mongolia, including selective migration, rural aging, and urban challenges like overpopulation and inequality. It highlights the inadequacy of current policy responses, emphasizing the need for legal frameworks, urban planning, and institutional coordination to manage climate mobility effectively. The chapter concludes that recognizing migration as a central element of adaptation and investing in proactive, inclusive governance are crucial for building resilience and achieving a more just and sustainable future in East Asia.