Bangladesh's capital, Dhaka, has one of the highest urban densities in the world and is one of the most crowded and quickly urbanizing megacities. The city's land use and land cover (LULC) has changed significantly in recent decades due to economic growth, population pressure, and infrastructural construction. The urban thermal environment is significantly impacted by these changes. From 1990 to 2025, this study examines the spatiotemporal link between land surface temperature (LST) and LULC changes in the Dhaka Metropolitan Area.We measured LULC transitions and associated LST fluctuations using a geospatial method that combines Landsat data, LULC classification, and LST retrieval by thermal band analysis. Significant urban development into arid land 22 km² and the conversion of vegetation 16 km² and water bodies 25 km² to urban areas are both revealed by the LULC change matrix.Urban regions have the highest mean temperature 21.05 °C, followed closely by arid terrain 21.26 °C, while vegetation has a slightly lower mean 20.59 °C, according to LST study. Water bodies, on the other hand, have a significantly lower mean temperature of 16.27 °C, underscoring their vital cooling role in the metropolitan thermal environment. Impervious materials and lower evapotranspiration have a significant impact on heat retention, as seen by the preservation of higher LST values in both built-up and bare surfaces.The results show that Dhaka's fast, uncontrolled development has resulted in the loss of water bodies as well as the extensive destruction of trees, green spaces, and vegetated regions. Impervious surfaces like concrete and asphalt have taken the role of these natural cooling systems, increasing heat retention and decreasing evapotranspiration. Because of this, LST in both populated and unpopulated areas are much higher, which exacerbates the Urban Heat Island (UHI) effect and fuels heat stress.