Does Urban–Rural Integration Promote Sustainable Development of a Low-Carbon Economy? Empirical Analysis of Panel Data from the Provincial Level in China

The key path to achieving global sustainable development is a low-carbon economy, which is of great significance for implementing the United Nations’ 2030 SDGs 7, 11, 12, and 13. Utilizing provincial panel data of 30 Chinese provinces spanning 2006–2024, this study explores the influencing pathways and intrinsic mechanisms of urban-rural integration (abbreviated as U-R integration) toward green low-carbon sustainable growth. Empirical results demonstrate that U-R integration prominently boosts regional low-carbon growth, and such conclusions pass multiple reliability verification procedures. Heterogeneity assessments demonstrate that the impact is most pronounced in eastern zones, whereas it proves insignificant or even adverse in central, western, and northeastern locales. The influence of U-R integration is notably stronger in less urbanized districts relative to highly urbanized ones. Mechanism analysis suggests that energy structure transformation and industrial structure transformation play an intermediary role. Further extended analysis shows that Internet development features a unique threshold characteristic; once the threshold is exceeded, it markedly strengthens the catalytic role of U-R integration. Furthermore, spatial spillover estimates reveal that U-R integration drives local low-carbon progress while delivering remarkable positive externalities to adjacent provinces. Accordingly, this paper proposes adopting region-specific strategies, reinforcing institutional arrangements and factor mobility support for central, western, and northeastern areas, and advancing U-R integration in line with local realities.