High-performance and corrosion-resistant microwave absorbers are required response to environmental degradation. Herein, monodisperse and superparamagnetic porous RGO@Fe3O4 nanocomposites are prepared by a simple one-pot method based on solvothermal treatment of Fe(acac)3 and graphene oxide solution. The as-prepared samples have been characterized using XRD, Raman spectroscopy, XPS, SEM and TEM. The magnetic properties and electromagnetic parameters analyses indicated that the nanocomposites show superparamagnetism with relatively high saturation magnetization and excellent electromagnetic wave (EMW) absorption properties. The minimum reflection loss (RLmin) and maximum effective absorption bandwidth (EAB) are − 65.7 dB and 6.0 GHz, respectively. Significantly, after hydrochloric acid treatment for 1 month, RGO@Fe3O4 hybrids still exhibited superior microwave absorption capabilities. It is suggested that our approach proposes an economic and green route for the controllable synthesis of porous functionalized graphene materials, a kind of corrosion-resistant synergistic microwave absorbers.