The reduced graphene oxide nanosheets (RGONs)@Fe3O4 hybrid nanosheets were prepared by coprecipitation method from graphene oxide (GO) and FeSO4 and FeCl3. A novel RGONs@Fe3O4/waterborne polyurethane (WPU) superfine fiber synthetic leather was obtained by physical blending and doctor-blading method. RGONs@Fe3O4 hybrid nanosheets were characterized by Raman, XPS, XRD, SEM and TEM. The electrical and magnetic characteristics and electromagnetic shielding efficiency of RGONs@Fe3O4/WPU ultrafine fiber synthetic leather were investigated. And the shielding mechanism was discussed. The results showed that under the condition of n(GO) ∶n(Fen+)=1∶10,〔Fen+ is a mixture with n(Fe2+)∶n(Fe3+)=1∶1.75〕, Fe3O4 nanoparticles were deposited uniformly on the surface of RGONs sheets, the composite structure effectively reduced the π-π stacking effect between RGONs nanosheets. With the increase of the amount of RGONs@Fe3O4 hybrid nanosheets, the electromagnetic characteristics of RGONs@Fe3O4/WPU superfine fiber synthetic leather were obviously improved. When the RGONs@Fe3O4 dosage was 5% (based on the mass of WPU, the same below), the electromagnetic shielding coefficient (EMI SE) of RGONs@Fe3O4/WPU superfine synthetic leather in the frequency range of 8.2~12.4 GHz could reach 36 dB, which was about 40% higher than that of RGONs/WPU superfine synthetic leather. The surface effect and electrical and magnetic double loss characteristics of RGONs@Fe3O4 hybrid nanosheets are the key mechanisms to enhance the electromagnetic shielding performance of RGONs@Fe3O4/WPU superfine fiber synthetic leather. The surface effect and electrical and magnetic double loss characteristics of the hybrid nanoflakes of RGONs@Fe3O4 are the key to enhance the electromagnetic shielding performance of the composite leather.