Groundwater management (quantity and quality) is a pressing concern in Islamabad amid the challenges posed by climate change and urbanization. This study leverages the Water Quality Index (WQI), coupled with advanced remote sensing (RS) and geographic information system (GIS) applications, to provide a comprehensive assessment of groundwater dynamics in the city. Groundwater samples from 40 tube wells were analyzed using standard methods, and spatial distribution patterns of water quality variables were mapped applying an integrated GIS framework. Geological and hydrological data collected from the Capital Development Authority (CDA) supported the mapping of water table depths, bore depths, and water quality features. Key findings revealed significant hydrogeological variations, with sectors G-8, G-7, G-9, and G-11 exhibiting elevated electrical conductivity (EC) levels, peaking at 1054.5 µS/cm, surpassing permissible limits. The WQI indicated excellent to good quality of all the collected samples except one found unfit for drinking. Land use and land cover (LULC) analysis revealed extensive urbanization, exacerbating groundwater contamination risks. This study underscores the interconnectedness of urban growth, geological features, groundwater quality deterioration, and sustainability. The findings provide actionable insights for policymakers and urban planners to mitigate groundwater contamination and ensure sustainable resource management in Islamabad.