Circular economy (CE) has emerged as a sustainable policy framework adopted by many countries to reduce waste generation through the application of the 5R principles: reuse, recycle, recovery, reclamation, and reduce. This mini-review summarizes recent studies on the application of circular economy approaches in wastewater treatment, highlighting their potential contributions to sustainable development through resource conservation, waste minimization, and pollution reduction. CE-based wastewater treatment systems can also support climate change mitigation by improving energy efficiency and enabling energy recovery, while contributing to ecosystem protection through reduced pollutant discharge and the promotion of closed-loop material flows. This review discusses representative circular economy models for recovering water, valuable materials, and energy from wastewater, and outlines key strategies to address current limitations while strengthening opportunities for implementation. Overall, the integration of circular economy principles into wastewater treatment is emphasized as a promising pathway toward more sustainable and resilient water management systems.