Abstract: As a pivotal measure for unleashing national foundational strategic resources, government public data opening is profoundly reshaping market information environments and corporate decision-making paradigms. Leveraging data from A-share listed companies spanning 2007 to 2023 and employing the staggered rollout of government data platforms since 2012 as a quasi-natural experiment, this study constructs a theoretical framework of “data information supply—corporate behavioral constraints—environmental performance improvement.” Using difference-in-differences (DID) models, we evaluate the impact and heterogeneous features of government public data opening on corporate environmental performance, and innovatively explore its underlying mechanisms from the perspectives of corporate investment-financing and internal-external governance. Our findings indicate that government public data opening enhances corporate environmental performance, and this conclusion remains valid after a series of robustness tests. Mechanism analyses reveal that this effect operates through four primary channels: stimulating environmental investments, alleviating financing constraints, strengthening external monitoring, and improving internal decision-making quality. Heterogeneity analyses further demonstrate that the enabling effect is more pronounced among firms with lower perceived economic policy uncertainty and higher managerial green awareness, in industries with weaker competition or technology-intensive attributes, and in cities with superior new digital infrastructure or stricter environmental regulations. This paper not only expands the theoretical frontiers of digital governance and corporate environmental responsibility but also provides compelling empirical evidence on how data elements can empower corporate environmental governance and facilitate green transitions.