Polymer-derived ceramics (PDCs), such as SiOC, SiCN, SiBCN, and SiC are considered the best candidates for designing high-performance microwave absorber due to their controllable structure, homogeneous element composition at atom level, tunable electromagnetic and electrochemical properties. Herein, Fe ions doped silicon oxycarbide (Fe ions-SiOC) ceramics have been successfully fabricated via solvothermal method. The electromagnetic absorption performances of the nanocomposites prove to be controllable via tailoring Fe ion contents. The Fe ions effectively enhance both the interfacial polarization of amorphous SiOC, and the dielectric properties of the nanocomposites but barely effect magnetic properties of the nanocomposite. As for 0.16 mol/L-SiOC ceramics annealed at 1450 degrees C, the effective absorption bandwidth as high as 2.00 GHz and reflection loss of -59.60 dB at 5.40 GHz with the thickness of 4.55 mm are obtained. Such work opens up a novel and simple route to scale up the PDC-based materials with broadband and excellent microwave absorbing performances.