Global warming, caused by an increase in carbon emissions, is a phenomenon that has attracted considerable attention worldwide. Financial development affects technological progress and carbon emissions. Based on the provincial panel data of 30 provinces and cities in China from 2006 to 2018, combined with the heterogeneity of technological progress, this study constructs an intermediary effect model for empirical analysis. Combined with different regional characteristics in the east, middle, and west of China, this study explores the impact of financial development on carbon emissions and the transmission path of heterogeneous technological progress as an intermediary variable. The results show that at the national level, in the eastern and central regions, the relationship between financial development and carbon emissions conforms to the characteristics of Environmental Kuznets curve, and the relationship between financial development and carbon emission in the western region increases linearly. Among the intermediary effect transmission paths of heterogeneous technological progress, generalised technological progress, environmental technological progress, energy technological progress, capital embodied technological progress and FDI technology spillover are the transmission paths of financial development on carbon emissions at the national level. However, after the regional division of the east, middle, and west, heterogeneous technological progress shows different carbon emission reduction effects. Through quantitative analysis, this study provides reference suggestions for financial development to help reduce carbon emissions, to prevent the emergence of ‘one size fits all’ technology policy or regional overall planning concept.