This study empirically examines the interplay between market integration and economic growth across nine cities within the Pearl River Delta urban agglomeration. The findings indicate that the city cluster’s market integration negatively impacts regional economic development and has a negligible effect on the surrounding areas. In response, the research recommends the elimination of market trade barriers and a reduction in local protectionism within the city cluster. Additionally, infrastructure enhancement is essential to leverage the distinct comparative advantages of each city within the Pearl River Delta urban agglomeration. An efficient collaboration mechanism is crucial to amplify the collective economic potency of the region.