Can Smart City Construction Enhance Ecological Welfare Performance?—Empirical Evidence from Chinese Cities

Against the backdrop of a polycrisis shaped by the interaction of climate change, resource constraints, and digital transformation, urban ecological welfare performance (EWP) captures cities’ ability to achieve higher welfare outcomes while limiting resource consumption and environmental costs. It also indicates their capacity to sustain green development and welfare provision under multiple pressures. Using panel data for 242 prefecture-level cities in China from 2008 to 2023, this study measures urban EWP with a super-efficiency slacks-based measure (SBM) model. It then treats China’s national smart city pilot policy as a quasi-natural experiment and applies a multi-period difference-in-differences (DID) model to estimate the effect of smart city construction (SC) on EWP. The results indicate that SC significantly improves EWP, and this finding remains robust across a range of sensitivity tests. Mechanism analyses provide evidence consistent with resource allocation optimization and green technological innovation as two potential channels. Relatively larger estimates are observed for cities in northeastern China, large cities, and non-resource-based cities. The interaction estimates further suggest that greater fiscal investment intensity and higher internet penetration strengthen the positive relationship between SC and EWP. These findings support the context-sensitive implementation of smart city strategies and coordinated improvements in ecological sustainability and residents’ welfare.