Abstract: Land Surface Temperature (LST) is one of the prominent methods to conduct climate studies and commonly used to analyze the impact of land surface changes all over the world. Due to many anthropogenic activities, natural environment transformed into urbanized areas rapidly. As a result, certain climatic components including land surface temperature has been modified dramatically. Therefore, this study was conducted to estimate Land Surface Temperature (LST) in highest population growth cities in Sri Lanka. The main objective of this research was to examine the relationship of rapid urban population growth with Land Surface Temperature using Geographical Information System (GIS) and Remote Sensing (RS) techniques. The study was conducted in five cities in Sri Lanka and those cities were selected by the population growth rate.