Impact of Digital-Green Policy Combination on Urban Inclusive Green Growth: Evidence from China’s Dual Pilot Policies of Smart City and Low-Carbon City

To examine whether combining the smart city pilot policy with the low-carbon city pilot policy contributes to urban inclusive green growth, and to investigate the effects and underlying mechanisms of this policy combination across different implementation scenarios, this study takes 262 Chinese cities as its sample and uses data from 2011 to 2023 for empirical analysis. The study defines the digital-green policy combination according to whether both pilot policies are in effect and adopts a multi-period difference-in-differences model to estimate its effects. Empirical results indicate that the digital-green policy combination positively affects urban inclusive green growth, with a coefficient of 0.1395 (p < 0.01). Tests by city type reveal that, compared with non-pilot cities and single-pilot cities, the digital-green policy combination yields incremental benefits for urban inclusive green growth. Analyses by policy implementation phase show that the coefficient of the dual-pilot phase is 0.2192, which exceeds the coefficients for the smart city pilot-only phase and the low-carbon city pilot-only phase by 0.1660 (p < 0.01) and 0.0984 (p < 0.05), respectively. Mechanism analysis shows that the digital-green policy combination negatively affects carbon emission intensity, with a coefficient of −0.2040 (p < 0.05), and that carbon emission intensity plays a mediating role. Both digital knowledge flow and green finance positively moderate the impact of the digital-green policy combination on urban inclusive green growth. Further analysis reveals that both the “smart city policy first” and “low-carbon city policy first” sequences have positive impacts on urban inclusive green growth, but their effects do not differ significantly. The time interval between policy implementations does not significantly moderate the impact of the digital-green policy combination on urban inclusive green growth. The digital-green policy combination significantly promotes inclusive green growth in key environmental protection cities, cities with ecological compensation, cities without ecological compensation, cities with high digital talent and cities with low digital talent. The differences in coefficients between groups classified by key environmental protection status and ecological compensation status are both statistically significant, whereas the differences in coefficients between groups classified by digital talent levels are not statistically significant. Positive spatial spillover effects are also identified, indicating that the benefits of the digital-green policy combination extend to other cities through economic–geographic linkages.