Rapid urbanisation in Enugu Metropolis has increasingly altered natural hydrological processes, raising concerns about groundwater sustainability and aquifer vulnerability. This study assessed the impact of urban expansion on groundwater recharge and evaluated the susceptibility of the underlying aquifers to contamination. An integrated approach involving hydrogeological field measurements, laboratory analyses, geospatial land-use assessment, and DRASTIC vulnerability modelling was employed. Land-use/land-cover analysis showed that built-up areas expanded from 18% in 2000 to 52% in 2024, while vegetation cover declined by 31%, indicating significant surface sealing. Groundwater level measurements revealed depths ranging from 9.4 to 28.7 m, with reduced recharge in densely urbanised zones. Estimated recharge decreased from 142–170 mm/year in 2000 to 68–110 mm/year in 2024, representing a 39–52% decline. Hydrogeological analysis showed moderately productive sandstone aquifers with hydraulic conductivity of 1.4 × 10⁻⁴ to 6.2 × 10⁻⁴ m/s and transmissivity values of 15.8–64.3 m²/day. Groundwater quality showed slightly acidic pH (5.2–6.8) and elevated nitrate concentrations (up to 64 mg/L), indicating anthropogenic influence. The DRASTIC model classified 35% of the metropolis as highly vulnerable, 49% moderately vulnerable, and 16% of low vulnerability, with high-risk zones concentrated in Abakpa Nike, Ogui, Emene, Uwani, and Trans-Ekulu. The study concludes that rapid urbanisation has significantly reduced groundwater recharge and heightened aquifer vulnerability in Enugu Metropolis. It recommends improved urban planning, protection of recharge zones, enhanced waste management, and establishment of a groundwater monitoring network to ensure long-term water resource sustainability.