High stability and efficient charge separation are two critical factors to construct high-performance photocatalysts. Here, an efficient strategy was provided to fabricate the nanocomposite of graphitic carbon nitride/ferroferric oxide/reduced graphene oxide (g-C₃N₄/Fe₃O₄/RGO). The degradation of rhodamine B (RhB) by g-C₃N₄/Fe₃O₄/RGO nanocomposite followed the pseudo-first-order kinetics. The g-C₃N₄/Fe₃O₄/RGO nanocomposite exhibited excellent stability and magnetically separable performance. It was ascertained that the quantum efficiency and separation efficiency of photoexcited charge carriers of g-C₃N₄/Fe₃O₄/RGO nanocomposite were obviously improved. Particularly, the g-C₃N₄/Fe₃O₄/RGO nanocomposite with 3 wt.% RGO presented 100% degradation efficiency under visible light irradiation for 75 min. The remarkable photocatalytic degradation activity is attributed to the synergistic interactions among g-C₃N₄, Fe₃O₄, and RGO, along with the efficient interfacial charge separation.