Integrating the digital economy into the real economy (thereafter referred to as digital-real integration) is one of the important ways to promote the efficiency improvement of green development. We adopt the panel data of 30 provinces and cities in China (excluding Tibet, Hong Kong, Macao, and Taiwan) from 2011 to 2021 as the basis of our study. We also use the coupled coordination model to measure the level of digital-real integration in each region. Then, we set up a spatio-temporal geographically weighted regression model to examine the spatio-temporal distribution pattern and the specific mechanism of its impact on the efficiency of regional green development. Our study finds that the vast majority of provinces in the country are in the coupling and coordination state on the verge of dysfunction and mild dysfunction. Moreover, coordinating with the development speed of the digital economy to reach the state of dynamic interconnection and constraints is difficult for the real economy. Second, the level of digital-real integration can contribute to the improvement of green development efficiency, and that in Xinjiang and Qinghai is lower than in other provinces. Further in terms of spatial distribution, the digital-real integration in the Yangtze River Delta region (Shanghai, Jiangsu, Zhejiang, Anhui) and Fujian Provinces during the 11-year period obviously promotes the efficiency of green development. Finally, through the mechanism analysis, the digital-real integration development can be found to promote the improvement of green development efficiency via three channels: industrial structure rationalization, factor market development degree, and government intervention. Findings of this paper provide some basis and reference for better promoting the digital-real integration and then realizing the long-term sustainable development of the region. [ABSTRACT FROM AUTHOR]