The application of graphene-based nanomaterials for microwave absorption has been hindered by high conductivity and excessively high dielectric loss . A promising approach to address this challenge is achieving impedance match by utilizing ferromagnetic graphene while simultaneously suppressing conductivity. In this study, we explored B-doped and Co-decorated graphene ( GBCoαα ) for this purpose . Density Functional Theory ( DFT ) and theoretical calculations were employed to compute impedance parameters and reflection loss . The nanocomposite exhibited distinctive dielectric properties attributed to charge transfer at the GBCo interface, leading to outstanding microwave absorption performance over a broad frequency range . Specifically, compared to GCo22, GCo33, and GBCo33 nanocomposites, GBCo22 demonstrated superior microwave absorption efficiency ( reflection loss, RL = -42.02 dB ) due to its favorable impedance matching and a well-balanced interplay of dielectric and magnetic losses . The results indicate that in the frequency range of 2-18 GHz, the proposed structure exhibits a reflection loss below -10 dB.