This study explores the relationship between firms' biodiversity risk and bankruptcy risk, drawing on data from U.S. companies spanning 2004 to 2020. Our analysis yields several important insights. First, we find a negative association between biodiversity risk and distance-to-default, suggesting that firms exposed to ecological degradation face heightened financial distress and an increased likelihood of default. Second, the effectiveness of both internal governance mechanisms and external ESG evaluations emerges as a key factor in moderating this relationship. In particular, the negative impact of biodiversity risk on financial stability is more pronounced among firms with greater gender diversity on their boards and stronger ESG ratings. Gender-diverse boards reflect a firm's stronger commitment to biodiversity issues, improved internal oversight, and reduced information asymmetry. ESG ratings, as external indicators, capture a firm's social capital, stakeholder-oriented values, and trustworthiness—factors that collectively support more robust biodiversity risk management.