The digital economy is becoming a new driving force for economic and social development in Chi- na and has a profound impact on narrowing the green innovation gap among cities and promoting coordinated ur- ban development. Using panel data from 279 prefecture-level cities in China from 2008 to 2021, this study ex- amines the impact of the digital economy on the green innovation gap among cities and its underlying mecha- nisms. The findings show that the digital economy can significantly reduce the green innovation gap among Chi- nese cities. Heterogeneity analysis indicates that this narrowing effect is more pronounced in regions with lower levels of marketization and in the eastern region. Mechanism analysis reveals that the improvement of resource allocation efficiency and industrial structure upgrading are important channels through which the digital economy narrows the green innovation gap. Network infrastructure development plays a homogeneous moderating role in the digital economy and the urban green innovation gap. Further research finds that the digital economy has a threshold effect on the green innovation gap in cities and the narrowing effect on the urban green innovation gap has the advantage of posteriority with increasing marginal rewards. To this end, cities should actively promote the construction of network infrastructure, formulate differentiated digital economy strategies, promote the upgra- ding of industrial structure, and facilitate the efficiency of resource allocation, so as to narrow the urban green innovation gap in a more effective way.