This study investigated the impacts of rapid urbanization on flow regime and ecosystem services across seasonal scales by integrating universal and seasonal IHA. Based on these indicators, hydrological alteration, the Range of Variability Approach, eco-surplus/deficit, and the Shannon Index (SI) were applied to evaluate the effects of urbanization. This comprehensive approach provided an improved perspective across both annual and seasonal time scales, observing the sophisticated impacts of urbanization on water cycle and ecosystem. The results indicate that urbanization has disrupted runoff systems, intensifying seasonal disparities in water availability and increasing the frequency of extreme flow events. These changes would weaken the adaptive capacity of watersheds, particularly during transitional periods between high- and low-flow seasons, where resource imbalances were most pronounced. From an ecosystem service perspective, urbanization has aggravated extreme deficits, disrupted the temporal consistency of biodiversity, and diminished the functionality of water conservation areas. The overall findings underline the need for season-specific strategies to effectively manage hydrological shifts and the importance of adaptive management strategies to lessen seasonal hydrological gaps and support ecosystem resilience.