This study explores the intricate relationship between urbanization, environmental quality, and human health across 20 countries with varying levels of urban development from 2021 to 2024. Using a combination of environmental monitoring data and public health surveys, we analyze how urbanization - driven factors such as air pollution, water contamination, and green space reduction affect key human health indicators including respiratory diseases, cardiovascular disorders, and mental health issues. The results indicate that rapid and unplanned urbanization is strongly associated with declining environmental quality and increased health risks, particularly in developing countries. However, well - designed urban planning strategies, such as improved waste management and expanded green infrastructure, can mitigate these adverse effects. This research provides valuable insights for policymakers to formulate effective measures that balance urban growth with environmental protection and public health promotion.