To investigate the impact of the digital economy on urban green development and its fluctuations, the entropy method is employed to measure the degrees of the digital economy and green development in 284 cities of China during 2013 to 2019. A panel fixed-effect model is established for the exploration of how the digital economy affects urban green development. The results indicate: (1) Throughout the research period, notable variations were observed in digital economy and green development levels among cities, both of which demonstrated an upward trajectory overall. After undergoing several robustness tests, it is evident that the digital economy plays a significant role in advancing urban green development. (2) The impact of the digital economy on urban green development varies due to differences in urban resource endowments and geographical locations. In non-resource-based cities and the eastern regions, the positive influence of the digital economy on urban green development is more pronounced and significant. (3) The effect of the digital economy on urban green development does not follow straight-line characteristics. When the digital economy level attains a specific threshold, its positive impact will notably intensify. The results aid in shaping specific policies for different regions, promoting digital economic growth, and facilitating the urban green transformation.