<p>As the economic core where the “Belt and Road Initiative” and the Yangtze River Economic Belt converge, the Chengdu-Chongqing Urban Agglomeration plays a crucial role in building a unified national market. Based on the statistical data of 11 major cities in the Chengdu-Chongqing Urban Agglomeration from 2011 to 2022, this paper explores the impact of market integration on regional economic growth and analyzes the mechanism of action and policy implications. The results show that from 2011 to 2022, the level of market integration in the Chengdu-Chongqing Urban Agglomeration has shown a fluctuating upward trend, and it has a significant positive impact on economic growth. Factors such as human capital, opening up, consumption level, and industrial structure also have a significant promoting effect on economic growth. The effect of market integration on economic growth exhibits a non-linear “inverted U-shaped” characteristic and shows spatial heterogeneity. The market integration effect in developed cities is gradually weakening, while there is still considerable room for improvement in less developed cities. </p>