This study investigates the impact of green supply chains on firms' environmental information disclosure, utilizing the Supply Chain Innovation and Application Pilot Policy (SCIAPP) as a quasinatural experiment. It explores the policy's effect by employing a difference-in-differences (DID) model with panel data from A-share listed firms in China spanning from 2012 to 2021. The findings indicate that, firstly, SCIAPP significantly enhances environmental information disclosure among pilot firms, suggesting that green supply chains foster such disclosures. Secondly, SCIAPP's impact mechanism involves improving executives' environmental awareness and bolstering external media scrutiny. Thirdly, SCIAPP's effect is more pronounced in firms with stronger internal controls and those located in regions with higher environmental concerns. Based on these conclusions, the study proposes recommendations to advance the development of green supply chains and promote firms' environmental information disclosure.