Green development is an inherent requirement for effectively responding to severe resource and environmental problems and adapting to major economic and social problems. Based on the panel data of 272 prefecture-level cities in China from 2011 to 2018, this paper takes the next-generation Internet model city policy as a quasi-natural experiment for the first time, and uses the DID model to empirically test the impact and mechanism of the next-generation Internet model city construction on green total factor productivity (GTFP). The results show that the next-generation Internet demonstration city has a significant role in promoting GTFP, and after being rated as a next-generation Internet demonstration city, its GTFP has increased by about 6.3%. This conclusion is still valid after a series of robustness tests, From the mechanism analysis, it is concluded that the next-generation Internet demonstration cities mainly promote GTFP through industrial structure optimization and technological innovation. A further test of heterogeneity shows that the construction of next-generation Internet demonstration cities is more significant in promoting GTFP in large-scale cities and resource-based cities. The research in this article provides a wealth of empirical evidence for the implementation of my country’s next-generation Internet model city policies.