When formulating international economic cooperation agreements, policymakers should consider not only their economic promotion effects but also their impact on green development. This paper is an examination of whether the Belt and Road Initiative contributes to green innovation quality. Objectively assessing the green innovation promotion effects of its implementation is not only important for its completion and improvement in the future, but also to verify whether the Belt and Road Initiative promotes sustainable development in participating regions. A difference-in-difference model was constructed using the data of 291 cities in China from 2008 to 2019. The results show the following: (1) the Initiative has significantly improved the quality of green innovation in cities along the Belt and Road; (2) a series of robustness tests showed that the main results are highly robust; (3) the Belt and Road Initiative has a significant policy spillover effect—while improving the quality of local green innovation, it can also significantly promote the quality of green innovation in surrounding areas. This paper has reference significance for further understanding the policy effect of China’s Belt and Road Initiative and the promotion and strengthening of subsequent policies.