Energy is the driving force behind economic development. The low-carbon transformation of the energy structure (the following may be referred to as LCT) contributes to balancing development and emission reduction. Green finance serves as a significant financial tool for LCT, yet relevant academic research in this area remains scarce. Based on panel data from 30 provinces in China spanning from 2007 to 2021, this paper analyzes the impact of green finance on LCT. The study draws the following conclusions: Green finance has significantly promoted LCT. Using green finance and green innovation as threshold variables, the impact of green finance on LCT exhibits a single threshold effect. Beyond the threshold value, green finance significantly enhances its role in improving LCT. Moreover, green finance exhibits spatial spillover effects on LCT, concurrently improving local and other regions’ LCT. Lastly, the study provides corresponding policy recommendations focusing on vigorously developing green finance, continuously enhancing green innovation capabilities, and leveraging the regional spillover effects of green finance.