The Yellow River Basin’s ecological protection and high-quality development (EPHD) are of practical significance for China’s economic development and ecological security. We take 103 cities in nine provinces along the Yellow River as research samples and measure green economy efficiency (GEE) and green finance (GF) based on balanced panel data from 2011-2021. We utilize the fixed effect and mediation effect models to explore the impact of GF on EPHD. We find that (1) the GEE of cities in the middle and upper reaches of the Yellow River Basin has significantly improved, and the stability in the lower reaches is better than in the upper reaches and shows a steady increase in GF development throughout the basin. (2) GF has a significant role in boosting EPHD. Green innovation, environmental regulation, and industrial structure are the supports for GF to play its role. (3) The impact of GF on EPHD is characterized by regional heterogeneity, and the GF enhancement effect is more obvious in low-pollution, high-financial expenditure, and highmarket- oriented cities. We focus on the supportive role of GF on EPHD in the Yellow River Basin, explain the mechanism and regional heterogeneity of this role, provide a theoretical basis for further promoting EPHD in the Yellow River Basin, and put forward specific policy recommendations in many aspects.