Abstract: With the ongoing promotion of ecological civilization, the factors driving corporate green decision-making and behavior have attracted significant attention. Using data from Chinese listed companies between 2009 and 2022, this study provides strong evidence that Confucianism, as an informal cultural system, plays a significant role in reducing corporate greenwashing. These findings suggest that the moral framework established by Confucianism profoundly influences corporate ethics, serving as a crucial social norm to curb unethical greenwashing practices. Further analysis confirms the mediating role of corporate green innovation capabilities in the relationship between Confucianism and greenwashing. Subsample regressions indicate that Confucianism significantly reduces greenwashing in regions with weaker regulations, whereas its effect is insignificant in areas with stronger regulations. The results remain robust across various sensitivity tests. These findings not only contribute to the theory of “culture and corporate decision-making” within an Eastern cultural context but also offer a new perspective for curbing unethical corporate behaviors, including greenwashing and promoting sustainable development.