This book chapter offers a holistic analysis of the multifaceted and reciprocal relationship between urbanization, migration, and social integration within the framework of contemporary social science literature. Cities are conceptualized not merely as spaces of high population density, but also as complex social spaces where inequalities, social encounters, and political tensions intensify. Migration is considered both a determinant and a consequence of the urbanization process; social integration is addressed as the most fragile and strategic dimension of this process. The chapter examines the historical transformation of urbanization within the context of the transition from industrial society to the global and neoliberal city; highlighting the effects of neoliberal urban policies on spatial segregation, housing problems, and the deepening of urban inequalities. Migration is analyzed through the distinctions of internal migration, international migration, and forced migration; and it is shown that factors such as wars, global inequalities, and the climate crisis have transformed cities into primary hubs for migration. Migrant concentration, ghettoization, and spatial exclusion processes are considered in conjunction with urban poverty and precarious employment. The concept of social cohesion has been addressed within a rights-based and mutually interactive framework, going beyond assimilation and integration approaches. It has been shown that structural inequalities in access to education, health, employment, and social services constitute the fundamental source of cohesion problems. Media discourses, discrimination, and prejudices have also been analyzed as significant factors weakening urban cohesion. Methodologically, the chapter is based on a qualitative research approach; it presents a theoretical synthesis through a comprehensive international literature review and conceptual analysis. The findings reveal that cohesion problems in cities stem more from spatial segregation, lack of institutional capacity, and policy incoordination than from cultural differences. In conclusion, the study emphasizes that inclusive urban policies, local-level cohesion programs, and multi-level governance models are critically important in strengthening social cohesion.