We report a facile method to produce a magnetically separable graphene oxide-magnetite nanocomposite (GO-Fe3O4) and its adsorption performance in methylene blue (MB) removal from aqueous solution. The GO-Fe3O4 nanocomposite was synthesized by a solution-phase self-assembly method including the incorporation of monodisperse Fe3O4 nanoparticles (NPs) and GO in a dimethylformamide/chloroform mixture under sonication. The successfully decorating GO sheet with monodisperse Fe3O4 NPs was proved by TEM study. ICP-OES data of the GO-Fe3O4 nanocomposite show that the GO-Fe3O4 nanocomposite consists of 21 wt% Fe 3 O 4 NPs, which is su ffi cient for its magnetic separation from aqueous solution. The spectroscopic studies reveal that the GO-Fe3O4 nanocomposite is a highly efficient adsorbent for MB removal from aqueous solution, providing an adsorption capacity of 172.6 mg/g, and the equilibrium for MB adsorption is attained in similar to 70 min. Moreover, it is a magnetically separable and reusable material for MB removal from water, preserving 87% of its initial e ffi ciency after 5 successive runs.