Does Urban–Rural Integrated Development Promote Eco-Environmental Quality? Evidence from China

The coordinated improvement of urban–rural integrated development (URID) and eco-environmental quality (EEQ) is a core strategic objective for pursuing sustainable development. However, existing studies have predominantly relied on qualitative discussions or single-region analyses, with insufficient empirical attention to multi-pathway mechanisms and spatial spillover effects. This study aims to examine the direct and heterogeneous effects of URID on EEQ, identify the dual mediating pathways, and quantify the spatial spillover effects across regions. Using panel data from 284 prefecture-level cities in China (2011–2023), this study employs panel regression, mediation analysis, and spatial econometric methods to investigate how URID affects EEQ. The results indicate that URID significantly promotes EEQ, with resource allocation efficiency and environmental regulation intensity serving as dual mediating pathways. This promoting effect varies across regions and policy stages. Moreover, URID exerts positive spatial spillover effects on neighboring regions. By providing national-scale evidence on mediating mechanisms and spatial externalities, this study extends prior research and offers implications for policy-making aimed at advancing the Sustainable Development Goals. The findings should be interpreted in light of the macro-level indicators employed and the observational research design.