Can Digital–Real Economy Integration Enhance Urban Green Innovation Efficiency? Evidence from Environmental and Intellectual Property Regulation Perspectives

Green innovation efficiency (GIE) serves as a key indicator of urban development toward “dual carbon” goals and sustainable growth. However, systematic evidence remains scarce regarding the impact of the digital-real economy integration (DRI) in urban green innovation efficiency (UGIE). Based on the dual institutional perspectives of government environmental regulation (ER) and intellectual property protection (IPP), this paper proposes an integrated theoretical framework that incorporates integration level, institutional environment, and green innovation. Leveraging panel data from 281 prefecture-level and higher-administered cities in China spanning 2013 to 2023, this paper explores the underlying mechanism and the observed threshold effect of DRI on UGIE. The primary findings are summarized below: (1) DRI promotes UGIE, which is mediated significantly through the institutional roles of ER and IPP. (2) The influence of DRI on GIE is characterized by a threshold effect at a value of 0.9657. Beyond this threshold, the marginal effect rises from 0.47463 to 0.52555, thereby providing evidence for the positive feedback hypothesis between integration level and institutional response. (3) A more significant effect of DRI on GIE could be observed in non-resource-based cities, such as the central cities, southern cities. This paper expands the interdisciplinary research on digital economy and urban sustainability, providing micro-level evidence for the tailored development of digital–green institutional combinations.