Urban green spaces (UGSs), i.e., parks, gardens, urban forests, and trees, are essential for improving environmental quality and reducing the effects of climate change, especially in fast urbanizing places like Dhaka, Bangladesh. The lack of green space in the city has a detrimental impact on public health and urban livability by causing problems like flooding, air pollution, and urban heat island (UHI) effects, which occurs when a city experiences much warmer temperatures than nearby rural areas. However, the significance of UGS and efficient policy execution are lacking. This study evaluates Dhaka’s urban green space (UGS) regulations and looks into ways to deal with these environmental issues. The study maps the spatial distribution of green spaces, assesses the health of the vegetation, and determines how they affect environmental quality using Geographic Information System (GIS)-based techniques, land use/land cover (LULC) analysis—which refers to the classification of human activities and natural features on the land using scientific and statistical analysis of source data—and normalized difference vegetation index (NDVI). Less than 8.5% of Dhaka’s land area is made up of green spaces, according to data research, and access varies significantly depending on socioeconomic status. Built-up area increased by 7.31% and vegetation declined by 7.89% from 2020 to 2024. Areas like Motijheel, Gulshan, Shahbagh, and Mirpur show very low NDVI values (<0.2) due to intense urbanization and lack of vegetation, contributing to heat retention. Low NDVI corresponds to high land surface temperature. There has been a decline in the urban green ecosystem—only 24% of Dhaka has thick vegetation, while 54% of the city has little to no vegetation. According to the data, places with less green space had hotter temperatures, worse air quality, and a higher chance of floods. The study suggests the need for comprehensive green infrastructure development in Dhaka to reduce UHI, improve air quality, and boost biodiversity, offering practical suggestions for urban policymakers.