Fe₃O₄ nanosheet arrays grown on both surfaces of graphene can be achieved by combining a mussel-inspired polydopamine adhesive and ethylene glycol-mediated process. Polydopamine is utilized not only as an efficient linker molecule that binds Fe₃O₄ nanosheets to the graphene, but also as a carbon source during heat treatment to yield the three dimensional (3D) graphene@carbon@Fe₃O₄ nanosheet arrays architecture. After the growth of Fe₃O₄ nanosheet arrays with accompanying reduction of graphene oxide into graphene, the 3D architecture exhibits outstanding microwave absorption properties. The simulated value of maximum reflection loss can reach −52.8 dB at 9.5 GHz with a sample thickness of 2.7 mm. The improved absorption capacity arises from the synergy of dielectric loss and magnetic loss, as well as the enhancement of multiple interfaces among graphene, carbon and Fe₃O₄ nanosheets. Furthermore, the synthesis strategy presented here can be expended as a facile approach to synthesizing related graphene-based 3D nanostructures for functional design and applications.