Corporate debt financing capacity is a critical factor for a firm’s survival and development. As climate change intensifies, examining the impact of climate risk on corporate debt financing is crucial for addressing climate change challenges. This study integrates data from the China Climate Risk Index (2007–2021) and A-share-listed companies on the Shanghai and Shenzhen stock exchanges, providing an in-depth analysis of the effects of climate risk on corporate debt financing and its underlying mechanisms. The research finds that climate risk significantly inhibits corporate debt financing, with a notable suppressive effect on both long-term and short-term debt financing. Mechanism tests indicate that climate risk suppresses corporate debt financing by weakening firm profitability, reducing asset turnover rates, increasing earnings uncertainty, and raising external financing costs. The moderating effect indicates that national climate risk responses mitigate the impact of climate risk on short-term debt financing while significantly suppressing long-term debt financing. Furthermore, corporate environmental information disclosure demonstrates a stronger inhibitory effect on short-term debt financing when climate risk is elevated. The study provides practical insights for firms and policymakers to address financing constraints under climate risks.