Circular economies are critical for alleviating resource pressure and improving environmental quality at regional level. Emergy analysis and eco-efficiency evaluations play important roles in measuring regional eco-efficiency and providing supporting information for governmental decision-making. In this study, emergy analysis and input–output analysis were applied to analyze the changes in emergy structure, functional efficiency, and sustainable development capacity of Zengcheng, Guangzhou during the period 2000–2016. The results showed that the proportion of non-renewable emergy in total emergy structure of Zengcheng increased from 55% to 75%, which placed a greater environmental load on the natural ecosystem and gradually weakened the capacity for sustainable development. The rates of emergy utilization and eco-efficiency both showed increasing trends. All indicators about eco-efficiency showed the development of Zengcheng heavily relied on emergy consumption, especially on non-renewable emergy. The relationship between emergy utilization and socio-economic development of Zengcheng can provide decision-making support for economic structure optimization and sustainable community development.