Abstract: Developing green finance is a pivotal strategy for achieving high-quality economic development. Based on panel data from 273 prefecture-level cities in China spanning 2006 to 2022, this paper measures indices for both green finance and high-quality economic development. It then comprehensively examines the impact of green finance on regional economic quality using mediation, moderation, and threshold models. The results indicate that green finance effectively fosters high-quality economic development, a conclusion that remains robust to endogeneity and various stability tests. This promotional effect is particularly significant in the eastern and central regions, cities with low financing constraints, and non-traditional industrial or resource-based cities, whereas it remains insignificant in other contexts. Furthermore, the impact exhibits a distinct threshold effect. From a supply-side perspective, green finance drives high-quality development by enhancing green economic efficiency and stimulating green entrepreneurship; from a demand-side perspective, it functions by raising public awareness of green consumption. Additionally, environmental regulation acts as a positive moderator in the relationship between green finance and economic quality. Based on these findings, local governments should implement context-specific green finance strategies, strengthen support for green entrepreneurship, refine supervision systems for project efficiency, and leverage environmental regulations to synergistically promote high-quality economic development across multiple dimensions.