Green Financial Reform, Financial Resource Allocation, and Digital–Green Synergy: Evidence from Chinese Cities

China’s Green Financial Reform and Innovation Pilot Policy may help coordinate digital and green transformation. Using a panel of 284 Chinese cities from 2011 to 2021, this study treats the policy as a quasi-natural experiment and estimates its effects with a difference-in-differences approach. The estimated effect of the reform on digital–green synergy is positive and receives marginal statistical support under small-treated-sample randomization inference. Mechanism analysis using city-clustered inference provides robust evidence consistent with a green-innovation pathway, while the evidence for local credit resource allocation is weaker and the environmental-governance pathway is not statistically supported. The estimated effect is larger in cities with weaker bank competition, provincial-capital and sub-provincial cities, and pilot regions targeting industrial upgrading. These findings suggest that green financial reform can support coordinated digital and green transformation, with its effectiveness varying across local financial and institutional conditions.