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Rapid urban expansion has intensified stormwater runoff and groundwater depletion due to increasing impervious transport infrastructure. Elevated corridors, while improving mobility, often exacerbate flood risk through conventional drainage systems that prioritize rapid discharge. This study evaluates a decentralized rainwater harvesting (RWH) system integrated within a 10.1 km elevated urban corridor in Coimbatore, India. More than 240 recharge pits were constructed and connected to the roadway drainage network to intercept and infiltrate runoff. Hydrological modelling indicates annual runoff generation of approximately 96,000 m³, of which nearly 81,800 m³ is effectively recharged into the subsurface aquifer. Peak discharge during high-intensity rainfall events is reduced by 15–20%, contributing to localized flood buffering. The recharge volume corresponds to avoid pumping energy of approximately 36,800 kWh per year and indirect carbon mitigation of 30–36 tonnes CO₂ annually. Over a 20-year period, the system yields an equivalent water value exceeding Rs. 11 crore.The study demonstrates that elevated corridors can function as multifunctional infrastructure supporting groundwater sustainability and climate resilience in rapidly urbanizing cities.