Heterostructured magnetic composites with exchange coupling effects are considered to be promising electromagnetic wave (EMW) absorbers. In this work, tailored heterostructures of soft magnetic ZnFe₂O₄ and hard magnetic Fe₃C are generated and tightly anchored on two-dimensional (2D) carbon nanosheets, by in-situ blowing and carbonization process of gel precursor. Nanosized soft/hard magnetic phases generate large number of heterogeneous interfaces. Density functional theory (DFT) calculations confirm the exchange coupling effect that results from the dynamic charges reconstruction of soft/hard magnetic heterogeneous interface. The synthesized Fe₃C/ZnFe₂O₄/C (FZC) shows wide EAB of 4.56 GHz and RL_min value of -65.6 dB. By layer-to-layer stacking of 2D FZC and reduced graphene oxide (rGO), the obtained flexible rGO/FZC-1 film can effectively shield 5G signals. Importantly, both the 2D morphology and abundant heterostructures restrain the diffusion of saline ions inside the FZC coatings and enhance the “maze effect”, finally improving the corrosion resistance in marine environment. This work provides advanced nanostructure integrating 2D morphology and soft/hard magnetic heterostructure with effective exchange coupling, which can simultaneously achieve the EMW stealth and high corrosion resistance.