Green innovation is considered an important way to promote low-carbon society formation and the sustainable development of environmental engineering. However, few quantitative studies have focused on the impact of intellectual property rights (IPR) on firm green innovation (FGI). This paper constructs a quasi-natural experiment based on the IPR pilot city policy in China. We empirically investigated the influence of IPR policy on FGI using a staggered difference-in-differences (DID) model and Chinese listed company data from 2007 to 2020. The findings of this research are as follows: (1) IPR policy significantly promotes FGI, and its effectiveness is confirmed by a variety of robustness tests. (2) The IPR policy supports both green product and green process innovation, with a stronger effect on green product innovation. (3) The IPR policy encourages green independent R&D but has little influence on green joint R&D. (4) The IPR policy promotes FGI with a high knowledge intensity, state-owned enterprises, and firms in key city groups. (5) The IPR policy supports FGI primarily via two institutional channels: increasing R&D investment and easing financing constraints. This paper broadens the study of green innovation city policy and FGI development, offering new perspectives for achieving social and environmental sustainability.

Urban forest policies have garnered increasing global attention for their critical role in providing key ecosystem services such as carbon sequestration, air pollution control, microclimate regulation, and biodiversity enhancement, as well as their potential to drive green innovation and sustainable urban development. This study utilized panel data from 273 Chinese cities between 2000 and 2022, employing a quasi-natural experiment and a difference-in-differences (DID) model to systematically evaluate the impact of the National Forest City Policy (NFCP) on urban green innovation. The results indicate that NFCP significantly enhances urban green innovation, with these findings remaining robust across a series of validation tests. Mechanism analysis revealed that the policy fosters green innovation by increasing environmental attention, facilitating talent aggregation, and reducing carbon emissions. Furthermore, heterogeneity analysis showed that the policy’s effects are more pronounced in small- and medium-sized cities, non-transportation hub cities, and economically developed regions. Based on these findings, this paper offers recommendations for optimizing policy implementation across different city types to further promote sustainable urban green economic development. This study broadens the research perspective on the relationship between urban policies and green innovation, providing more precise decision-making guidance for policymakers while also highlighting the important role urban forests play in enhancing ecosystem services and driving sustainable urban growth.