This study investigates the relationship between corporate environment and social (ES) performance and the governance factor by examining the effect of internal monitoring mechanisms on a firm's ES performance. We find that institutional ownership, especially pension investors, induces corporate ES performance. To address potential endogeneity concerns, this study employs the adoption of the Stewardship Code in Korea as a quasi-natural experiment, and we find consistent results. Outside directors also positively affect a firm's ES performance, and this positive impact is more pronounced with institutional investor holding, suggesting that internal monitoring for corporate ES performance might complement each other. Furthermore, a firm's better ES performance motivated by internal monitoring appears to bring a higher firm value. Overall, this study suggests that internal monitoring mechanisms can induce firms' non-financial performance and eventually contribute to shareholders' value.