A novel CeO₂ nanorod/g-C₃N₄/N-rGO ternary composite was synthesized using a simple ultrasonic-heat treatment method for application in the photocatalytic degradation of organic pollutants under the irradiation of visible light. This material shows superior photocatalytic activity compared with pure g-C₃N₄ and CeO₂ nanorods, and the photodegradation rate of RhB is up to 2.1-fold higher than that of the g-C₃N₄/N-rGO (at the optimum content of 0.25 wt% N-rGO) catalyst when the content of CeO₂ nanorods was 2 wt%. The enhancement of photocatalytic activity could be attributed to the synergistic effect among CeO₂, g-C₃N₄ and N-rGO (serves as a conductive network), which was found to lead to more efficient separation of photogenerated electron–hole pairs, resulting in the effective photodegradation of organic pollutants. In addition, superoxide radical anions (˙O₂⁻) and holes (h⁺) were considered as the main reactive species during the photodegradation process, and the ternary composite also exhibited preferable stability for the decomposition of RhB. This work provides an in-depth perspective for understanding the N-doped graphene-involved photocatalytic mechanism.