["Australian Accounting Review, EarlyView. ", "\nABSTRACT\nAs the global biodiversity crisis intensifies, corporate biodiversity commitments have emerged as a strategic response, yet their effectiveness lacks sufficient empirical evidence. Drawing on Shanghai and Shenzhen A‐share listed firms from 2015 to 2023, this study pairs three frontier large language models with researcher verification to detect biodiversity commitments in corporate sustainability disclosures, and examines how such commitments shape ESG performance. Firms that issue biodiversity commitments subsequently exhibit higher ESG ratings, and the relationship remains stable under alternative rating providers, instrumental variable estimation, Heckman selection correction, lagged‐treatment specifications, and an ordinal measure of commitment intensity. Committing firms subsequently report environmental information of higher quality and allocate more resources to environmental investment, with both channels carrying part of the effect. The relationship is more pronounced among heavily polluting firms and firms in provinces with stringent environmental regulation, suggesting that commitments deliver larger legitimacy returns where stakeholder scrutiny is most acute. The findings offer evidence on how firms translate environmental commitments into sustainable development performance and inform policy design for corporate ecological responsibility.\n"]