Synergizing Economic Growth and Environmental Sustainability: The Impact of Urban Land Agglomeration in the Yangtze River Delta

Urban Land Agglomeration (ULA) is continuously reshaping the way of urban spatial growth, emerging as a crucial pathway to balance economic growth and environmental sustainability. However, such economic‐environmental synergies remain unclear, posing challenges to sustainable urban development. This study, using panel data from China's Yangtze River Delta urban agglomeration (2006–2020), introduces the fixed effect panel regression model, mediating effect model, and spatial panel Durbin model to investigate the economic‐environmental effects of ULA, further exploring the intrinsic mechanisms and spatial spillover effects. The findings indicate that ULA can promote economic development and reduce environmental costs, thereby triggering the Porter effect. Technological innovation and industrial upgrading serve as key mechanisms in this process. Furthermore, ULA exhibits significant positive economic spillover effects, while its environmental spillover effects remain less pronounced. Heterogeneity analyses show that the Porter effect triggered by ULA demonstrates an enhancing trend, with more pronounced economic benefits in coastal cities and more significant environmental improvements in inland cities. The results of this study provide insights for promoting sustainable land management, integrated economic‐environmental governance, and region‐coordinated development strategies.