A novel FeO-graphene-biochar composite (GBC-FeO) was prepared to enhance the adsorption capacity and recollection efficiency of graphene-biochar composites (GBCs). The adsorption characteristics were tested to remove crystal violet (CV), which is a refractory compound in industrial wastewater. Structural and morphological analysis exhibited that a larger surface area, greater thermal stability, and more functional groups were present after FeO nanoparticles coated the GBC surface. This improved the CV adsorption versus uncoated GBC. The introduction of G and FeO nanoparticles collectively reduced the zeta potentials of GBC-FeO to -38.1 ± 1.1 mV versus -24.3 ± 2.2 mV for GBC and -20.7 ± 1.2 mV for BC. The maximum Q values were obtained 436.68 mg/g at 40 °C. Fourier transform infrared analysis suggested that the interactions of functional groups, such as aromatic C = C and C = O, -OH, C-C, and π-π played an important role in CV adsorption. The thermodynamic analysis of Langmuir and Freundlich isotherms indicated that the adsorption improved as a spontaneous endothermic process. The saturation magnetization of GBC-FeO reached 61.48 emu/g, allowing efficient recollection of the material with a magnet. The CV adsorbability of the re-collected GBC-FeO was 157.31 mg/g, which was slightly lower than freshly prepared GBC-FeO (199 mg/g). These findings demonstrated that GBC-FeO was an efficient and reusable multifunctional biochar.