Magnetic expanded graphite (EG) hybrids were synthesized by co-intercalation polymerization of aniline together with transition metal ions. Experimental results show that metal ions (Fe, Co, Ni, and Cu) and even their mixtures can co-intercalate into graphite interlayers with flexibly controllable ratios and contents. Among these co-intercalation compounds, Fe/Ni-intercalated graphite with a predesigned mole ratio of 1:3 transforms into NiFe₂O₄/FeNi₃@EG during the annealing process. The synthesized magnetic EG hybrids present multiband microwave absorption in C and X bands due to improved impedance match as well as significantly enhanced interfacial polarization relaxation induced by multi-componential metals. The reflection values of −39.1 dB at 6.95 GHz and −25.7 dB at 9.4 GHz are achieved with an ultra-low loading of 5 wt.%. This work provides a flexible approach for tuning the components and structures of magnetic EG hybrids, which may contribute to the development of microwave absorption materials with superior performances.