Ongoing urbanisation and climate change pose profound challenges for watershed hydrology, exacerbating flood risks and introducing uncertainties to urban stormwater management systems. This study aimed to enhance the understanding and management of a large mixed watershed, the Qinhuai River Catchment, facing intersecting urbanisation and climate change stressors. Hydrological modelling approach was applied to assess and quantify hydrological impacts from changes in catchment characteristics and climate conditions. Results showed land use/land cover changes increased rainfall-runoff conversion in urban areas. Certain rice paddy and dry agricultural land regions exhibited significant runoff generation potential requiring management attention. Consistent correlation between annual precipitation and streamflow highlighted the dominant role of precipitation in controlling runoff dynamics, but the study also identified the influence of temperature on monthly runoff formation. In general, the combined effects of precipitation and temperature played a crucial role in shaping patterns and fluxes of watershed runoff under changing environmental conditions.