Migration is a fundamental demographic process with profound consequences for population health globally. Increasingly driven by economic inequality, conflict, environmental change, and social transformation, migration shapes the distribution of health risks and opportunities across populations. While migration can improve socioeconomic conditions, enhance access to services, and contribute to economic development, it also introduces complex vulnerabilities related to infectious diseases, non-communicable diseases, mental health, maternal and child health, and occupational hazards. This paper provides an expanded examination of the multifaceted relationship between migration and health, analyzing underlying determinants, health system responses, and the lived experiences of migrants across different contexts. Drawing on contemporary scholarship and international frameworks, this review explores the health implications of migration in low-, middle-, and high-income countries, emphasizing structural drivers, health inequities, and the role of policy in shaping outcomes. The findings demonstrate that migrant health outcomes are shaped by interconnected social, political, and economic factors and require multisectoral and rights-based approaches to ensure equitable access to healthcare and protection of vulnerable populations. Drawing on evidence from global studies and country-specific experiences, including Nigeria, the European Union, and the United States, the article highlights key pathways through which migration influences population health. It concludes with recommendations for policy, health systems strengthening, and future research directions.