Environmental protection investment is crucial to achieving an environment-friendly society. This study explores the influence and mechanism of Confucianism on corporate environmental protection investment (EPI) from a long-term-oriented perspective. Calculating the density of Confucian academies in prefecture-level cities and using data on Chinese A-share listed companies from 2010 to 2020, this study finds that Confucianism plays a considerable role in promoting corporate environmental protection investment by stimulating corporations to assume social responsibility and ameliorate corporate accounting information quality. The positivity of Confucianism shows strong robustness. Further analysis shows that when environmental regulation is weak or industry competition is fierce, Confucian cultural values have a more positive influence on EPI. This study provides empirical evidence on incentivizing corporate environmental responsibility and comprehensive green transformation of economic and social development during the sustainable development phase.