<p>This study, based on panel data from 49 coastal cities in China from 2007 to 2019, combines the Tapio decoupling model with econometric methods to innovatively explore the impact of port development on the decoupling of urban development and hinterland pollution. The results of the Tapio decoupling model indicate that, with the continuous advancement of the Chinese government’s pollution reduction policies, 89.8% of coastal cities had achieved decoupling between urban development and environmental pollution by 2019. The panel cointegration test results reveal a long-run cointegrated relationship between port development and the decoupling of urban development-hinterland pollution. The findings from FMOLS and DOLS estimation techniques demonstrate that port development has significantly promoted the decoupling of urban development and hinterland pollution in China’s coastal cities. A heterogeneity analysis based on geographic regions shows significant regional differences in the impact of port development on decoupling. In the southeastern and southern coastal cities, port development has significantly facilitated the decoupling of urban development and hinterland pollution. However, in the Bohai Rim coastal cities, the goal of achieving decoupling through port development has not yet been fully realized.</p>