The growing focus on Environmental, Social, and Governance (ESG) in the investment market and society has prompted third-party rating agencies to provide comprehensive and objective ESG ratings for publicly listed companies. This study examines the environmental benefits of disclosing ESG ratings, particularly their impact on reducing toxic chemical emissions among U.S.-listed companies. By leveraging MSCI ESG data and the Toxics Release Inventory (TRI) data and applying a Difference-in-Differences methodology, we find that the disclosure of ESG ratings significantly reduces the release of chemicals regulated under the Clean Air Act (CAA). Further analysis reveals a complementary relationship between third-party ESG ratings and existing environmental regulations, demonstrating the positive role ESG ratings play in environmental governance. However, given the varying toxicity of chemicals and the limited impact of ESG scores, a more standardized, transparent, and credible scoring system is necessary to enhance the effectiveness of third-party ESG ratings in promoting sustainable development and enhancing social welfare.