This chapter examines the intersection of sociocultural integration and security within East Asia’s evolving migration regimes, focusing comparatively on Japan, South Korea, and Taiwan. Amid demographic decline and labor market demands, these countries have seen increasing migration inflows, yet their policy responses are marked by selective inclusion and securitized governance. Migration is often portrayed as a threat to social cohesion, cultural identity, and national security, hindering the development of inclusive integration frameworks. Employing a qualitative comparative methodology, the chapter draws on policy analysis, media discourse, and scholarly literature to assess how migrant integration is conceptualized and operationalized across these states. Guided by two theoretical frameworks—multiculturalism, which critiques institutional responses to diversity, and securitization theory, which exposes the framing of migration as a security issue—the chapter explores national variations. Case studies reveal Japan’s bureaucratic ambivalence, South Korea’s ethno-nationalist narratives, and Taiwan’s inclusive rhetoric tempered by structural constraints. The findings suggest that securitization undermines integration, reinforcing exclusion and precarious citizenship. The chapter advocates for a transition from control-oriented to rights-based approaches, emphasizing legal reform, inclusive identity narratives, and migrant participation. It concludes by proposing regional dialogue and cross-learning to address shared challenges and promote pluralistic futures.