<p>Complex interactions between land cover change, climate variability, and seasonal recharge processes shape groundwater dynamics in urban regions. This study investigates the hydrological impacts of urbanization and rainfall variability on groundwater levels (GWL) across four rapidly urbanizing districts in Eastern India, i.e., Kolkata, Khorda, Patna, and Ranchi, over a decadal period (2011–2021). Using a linear mixed-effects modeling (LMM) framework, the effects of built-up expansion, population growth, and precipitation on seasonal groundwater fluctuations were assessed, with groundwater levels disaggregated into four temporal categories: pre-monsoon minimum and maximum, and post-monsoon minimum and maximum. The model incorporates both fixed effects (urban and climatic indicators) and random effects (district-level heterogeneity), achieving a strong fit (R² = 0.961). Built-up area emerged as a statistically significant predictor of GWL, with its effect varying seasonally, particularly suppressing recharge during the pre-monsoon maximum phase. Population and rainfall showed limited direct influence, but exhibited significant interactions during dry periods, indicating that extraction intensity and rainfall-runoff dynamics jointly affect groundwater depletion. Spatial analysis revealed that model performance varied across districts, with highly urbanized areas, such as Kolkata, exhibiting more complex and less predictable aquifer responses. These findings demonstrate that urbanization modifies the seasonal timing and effectiveness of natural recharge, often decoupling rainfall from aquifer replenishment in densely built environments. The study highlights the importance of incorporating seasonal hydrological sensitivity into urban water management, providing valuable insights applicable to other data-scarce, rapidly urbanizing regions worldwide.</p>