The Indian Sundarbans, a globally significant mangrove ecosystem, is currently experiencing profound socio-spatial transformations driven by urban expansion, climate change, and anthropogenic activities. This study uses Geographic Information Systems (GIS) mapping and satellite imagery to analyze these transformations, particularly in Jaynagar, a transitional zone within the Sundarbans delta. Utilizing multi-temporal satellite data (2015–2024), the research maps and classifies Land Use and Land Cover (LULC) changes, evaluates Land Surface Temperature (LST), and computes indices such as Enhanced Vegetation Index (EVI), Normalized Difference Built-up Index (NDBI), and Normalized Difference Water Index (NDWI). The results indicate a complex interplay between urbanization and environmental degradation: despite an increase in vegetation cover, a decline in vegetation health (EVI) and a rise in LST were observed. Built-up areas showed a strong positive correlation with LST, while water availability (NDWI) exhibited a declining trend, further influencing thermal dynamics. The findings emphasize that unplanned urban growth contributes significantly to ecological stress, highlighting the necessity of integrated, geospatially informed strategies for sustainable land management and climate adaptation in the Sundarbans region. The result shows that, in the Indian Sundarbans, vegetation cover rose from 78.85 to 85.12% between 2015 and 2024, but vegetation health (EVI) decreased from 0.75 to 0.65. Cropland increased to 89.23% before declining slightly to 88.56%, while the amount of urban built-up fell from 97.32 to 91.45%. Marshlands and water bodies increased (88.10–93.22%; 75.34–79.45%), however surface wetness is decreasing according to NDWI trends. The land surface temperature (LST) increased significantly (37.99–46.63 °C maximum; 25.91–32.70 °C min), indicating that the urbanization-related urban heat island effects are more intense.