Green innovation is an important driving force for sustainable development of firms in China's strategic emerging industries. Solving the finance constraints of green innovation is an effective approach to realize this developmental goal. This paper uses the panel data of China's A-share listed firms in strategic emerging industries from 2013 to 2022 to empirically test the effect and mechanism of the fintech on firm green innovation. We find that the fintech can significantly promote firm green innovation, and firm digital transformation also has a positive effect on firm green innovation. Moreover, firm digital transformation is a conduit for the impact of the fintech on firm green innovation. In other words, the fintech facilitates firm green innovation by enhancing firm digital transformation. In addition, the heterogeneity analysis suggests that the effect of the fintech on firm green innovation of firms in eastern region is stronger than that of firms in central and western regions.