Abstract: A well-functioning environmental judiciary system plays a critical role in fostering green innovation and facilitating green transformation. Against the backdrop of China’s deepening environmental judicial reform, this study exploits the establishment of environmental courts as a quasi-natural experiment to empirically examine their impact on corporate green innovation, employing a multi-period difference-in-differences (DID) approach. The results reveal that environmental courts significantly enhance firms' green innovation, with a more pronounced effect on substantive green innovation. Unlike passive defensive responses driven by firm vulnerability, this effect is primarily driven by proactive self-regulation mechanisms. Further analysis shows that the effect is more salient in state-owned enterprises and firms with long-term managerial orientation, and that it diffuses through executive interlocks, producing a “chain effect.” This study contributes to the literature by introducing a judicial perspective to the determinants of green innovation and offers micro-level evidence on how environmental courts can incentivize sustainable corporate behavior. The findings also provide policy implications for enhancing environmental governance and promoting green development at the local level.