Improving the green total factor energy efficiency (GTFEE) is an important way to adhere to sustainable development. This paper evaluates the impact of fintech on GTFEE based on an SBM-Malmquist-Luenberger model with annual data from 2011 to 2021 of 240 cities in China. The findings reveal that fintech can significantly promote GTFEE and the conclusion remains robust after conducting the endogeneity test and substituting the independent and dependent variables. Specifically, the mechanism analysis indicates that fintech can improve GTFEE by alleviating financing constraints and promoting technological innovation. What’s more, fintech significantly enhances GTFEE in eastern China, non-resource-based cities, service cities, and larger-sized urban centers. This study provides valuable policy implications for promoting the energy efficiency.