Metal-free graphite carbon nitride (g-C3N4) has shown great potential in the environmental and energy fields. Herein, we illustrate the facile synthesis of Cr2O3-embedded g-C3N4 interlayer composites using an oil bath and thermal polymerization. The as-prepared 0.3-Cr2O3/g-C3N4 composite photocatalyst exhibited many excellent properties, including significantly promoting charge transfer and separation by establishing interlayer paths, having a large specific surface area, and significantly improving the light absorption intensity. Therefore, the composites of Cr2O3 embedded in g-C3N4 exhibit visible-light photocatalysis. After 50[Formula: see text]min of visible light illumination, the degradation rate reached 99%, which was approximately 9.5 times that of pure g-C3N4. Repeatability test results show that the prepared 0.3-Cr2O3/g-C3N4 catalyst has prominent stability and repeatability. Then, we explain the mechanism of RhB degradation using the synthesized photocatalyst. This work provides a reference for the comprehensive development of g-C3N4 and offers broad prospects for photocatalytic applications of other layered materials.