A city's ecology and energy use can be affected by an urban heat island (UHI). However, its role in exacerbating populations' heat stress has been extensively studied. This study reviewed and summarized the literature on the UHI, its causes, and its effects. After that, the characteristics of population heat stress vulnerability are examined. The results of studies on UHI, its health effects, and potential mitigation tactics in existing settlements show the necessity of examining various relationships between UHI and the locations of susceptible populations and possible responses. By examining literature from related domains, the present study intends to identify the research potential and convince researchers about the necessity of such a study in the urban area, especially in developing nations, since such case studies were only a few. Further, the study highlighted the relevance of urban planning to mitigate UHI. A fundamental examination of a city's urban climate can be the initial step in creating urban design standards, followed by research and models considering socio-economic and environmental elements.