The China Railway Express (CRExpress) is a vital international transportation infrastructure for the advancement of the Belt and Road Initiative and the expansion of international commerce, providing a significant opportunity for Chinese companies to undergo a sustainable transformation. We use a multi-period differences-in-differences model to investigate the relationship and mechanism between the opening of the CRExpress and green innovation of enterprises, based on the panel data of Chinese A-shared listed companies from 2007 to 2020. The results show that the opening of the CRExpress can significantly increase the logarithmic number of green patent applications by at least 5% in enterprises with a spoke radius of 250–450 km, and it also has a significant positive effect on different types of green patents to varying degrees. By examining the sub-items of ESG ratings, the opening of the CRExpress can promote the green innovation of enterprises through the improvement of E-score. Additionally, three pivotal mechanism pathways have been identified: the promotion of regional economic development, the alleviation of corporate financing constraints, and the reduction of corporate logistics expenses. Furthermore, we find that the effect of the CRExpress turns out larger on the green innovation of enterprises in the Secondary Industry and the Tertiary Industry, manufacturing industry, state-owned enterprises, and firms located in the eastern and central regions. Based on the empirical study, we provide policy implications for deepening the correlation between the CRExpress and green innovation.