China's Belt and Road Initiative (BRI), launched in 2013, is rapidly subsuming much of China's political and economic involvement abroad. As a far‐reaching infrastructure development and investment strategy, officially involving more than 130 countries, the expansion of the BRI raises important questions about its environmental impacts and its implications for environmental governance. This article examines how China is actively and rapidly developing an institutional architecture for its envisioned “green BRI,” considering the key actors, policies, and initiatives involved in the environmental governance of the BRI. We find that the current institutional architecture of the “green BRI” relies on voluntary corporate self‐governance and a multitude of international and transnational sustainability initiatives. The effectiveness of the environmental governance of the BRI not only hinges on China's priorities and commitments, but also on the political willingness and capacity of BRI partner countries to maintain, implement, and enforce stringent environmental laws and regulations. We conclude by outlining several environmental governance challenges and an agenda for future research.