This paper empirically explores whether financial flexibility significantly affects corporate green innovation performance (CGIP), and by what means? What factors moderate the relationship between financial flexibility and CGIP? Are there differences across different types of firms, regions and industries? This study demonstrates that financial flexibility significantly enhances CGIP. Financial flexibility primarily facilitates green innovation by reducing corporate risk-taking and increasing non-efficiency investments. ESG performance negatively moderates the connection between financial flexibility and CGIP, while market competitiveness exerts a positive moderating effect on this relationship. The impact of financial flexibility on CGIP is more pronounced for non-state-owned enterprises, companies in eastern China, and those in high-tech industries. Further analysis reveals that, compared to debt flexibility, cash flexibility has a more significant effect on improving CGIP. This study offers theoretical guidance and practical insights to enhance CGIP.