In the context of carbon peaking and carbon neutrality goals, the construction of new infrastructure plays an important role in coordinating economic growth and environmental sustainability. Based on the data of 30 provincial samples in China from 2005 to 2021, this paper constructs a two-way fixed effect model to deeply explore the impact of new infrastructure construction on carbon emissions and analyzes the moderating effect of green finance in this process. The study shows that there is a significant inverted “U”-shaped relationship between new infrastructure construction and carbon emissions, and green finance can negatively moderate this relationship; new infrastructure construction can significantly reduce carbon emissions in the eastern and central regions, but its emission reduction effect is not significant in the western region; in the eastern region, green finance can significantly negatively moderate the inverted “U”-shaped relationship between new infrastructure construction and carbon emissions, while this effect is not significant in the central and western regions. Based on this, fully leveraging the scale effect of new infrastructure construction and the empowering effect of green finance on it will inject strong vitality into China’s low-carbon transformation and sustainable development.