In light of China's objectives for carbon peak and carbon neutrality, there is an opportunity for fintech to leverage its technological advantages and enhance its integration with green finance (GF). This can bring about enhanced coverage and precision of financial services for green industries, facilitating the transformation towards a sustainable, greener, and low-carbon real economy. We investigate how fintech development influences the carbon emission reduction effects of GF utilizing a two-way fixed effects model with a panel dataset covering 30 provinces in China from 2011 to 2020. Our findings indicate that the negative impact of GF on carbon emissions (CE) is heightened in areas with high levels of fintech development. Furthermore, we notice regional disparities in how fintech development impacts the effectiveness of GF in reducing CE. Specifically, fintech has a statistically significant impact in the central and western regions, whereas its significance is absent in the eastern region. Lastly, our mechanism analysis reveals that fintech plays a vital role in enhancing GF's capacity to mitigate CE, which is achieved through channels of promoting green technology innovation (GTI), alleviating corporate financing constraints (FC), and optimizing energy structure (ES). These findings provide compelling evidence for the positive effect of fintech on the environment and offer justification for promoting the development of fintech and GF.