<p>This study investigates the socio-economic and environmental factors influencing urban heat island (UHI) intensity in a rapidly urbanizing coastal megacity, Chennai Metropolitan Area (CMA), India. To fulfill the objective, the research analyzed sixteen factors across three key dimensions: social, economic, and environmental. Using correlation analysis and multiple regression, the study assessed the impact of socio-economic and environmental factors affecting UHI intensity in CMA. The findings revealed a significant increase in built-up areas by 133% and a corresponding decline in vegetation cover by 59% over the two decades. UHI intensity displayed spatial heterogeneity, with higher intensity areas predominantly concentrated in the middle-eastern and northern parts of CMA. Areas experiencing high and very high UHI intensity saw an alarming increase of 51.99–111.67%. The study found that socio-economic factors, such as population density and the working population, were positively correlated with UHI intensity, while environmental factors like normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) had a negative correlation, emphasizing their crucial role in mitigating UHI. The research is limited to the CMA, suggesting that further studies could explore similar urban settings in other regions. The findings highlight the importance of integrating environmental components with socio-economic planning to effectively address UHI intensity. This study offers novel insights into the role of socio-economic and environmental factors in UHI formation and intensification in cities, underscoring the need for targeted urban planning strategies to enhance environmental sustainability and livability.</p>