Digital finance is an innovative financial model of great significance for sustainable economic growth. By constructing indicators of sustainable economic growth, we explore the impact of digital finance on sustainable economic growth using the fixed effect model, mediating effect model, threshold regression model, and dynamic spatial Dubin model. The study finds that digital finance can drive sustainable economic growth, and the robustness and endogenous treatment results strongly verify this. Digital finance promotes sustainable growth mainly through technological innovation. In addition, with technological innovation and the development of renewable energy, there is a significant nonlinear relationship between digital finance and sustainable economic growth. Finally, the spatial spillover effect results show that digital finance's impact on sustainable economic growth has a positive effect, whether it is a direct effect or an indirect effect. This article provides possible ideas for digital finance to promote sustainable economic growth.