This study investigates the features and effects of the Belt and Road Initiative (BRI) on China's policy banks' overseas renewable energy development finance in BRI countries. To this end, this study uses the financing for energy projects' data in China's Global Energy Finance database and performs regression analysis using Differences-in-differences (DID) and Difference-in-differences-in-differences (DDD) methods. The main findings are as follows. First, compared with non-renewable energy finance, the BRI can increase the number of renewable energy projects financing by China's policy banks in BRI countries; however, this positive effect is mainly reflected in hydropower projects and Southeast Asia. Second, from the perspective of the providers' features, the BRI has a more significant role in promoting the financing of renewable energy by China Export and Import Bank. In terms of recipients' features, China's development finance is mainly directed to high credit risk, low-income countries and regions that traditional donors have disregarded; thus, the policy banks tend to cooperate with government recipients. Third, the BRI has facilitated China's policy banks' renewable energy finance in high carbon intensity countries, breaking the carbon lock-in effect and strengthening renewable energy financing through the establishment of energy partnerships, reflecting the features of joint contribution and cooperation. Our findings alleviate some scholars' concerns about the environmental effects of the BRI to a certain degree and show that proactive policies of investing countries can guide development finance to contribute to the global energy transition and climate goals.