Abstract: Carbon-based foams with a three-dimensional structure can serve as a lightweight template for the rational design and controllable preparation of metal oxide/carbon-based composite microwave absorption materials. In this study, a flake-like nickel cobaltate/reduced graphene oxide/melamine-derived carbon foam (FNC/RGO/MDCF) was successfully fabricated through a combination of solvothermal treatment and high-temperature pyrolysis. Results indicated that RGO was evenly distributed in the MDCF skeleton, providing effective support for the load growth of FNC on its surface. Sample S3, the FNC/RGO/MDCF composite prepared by solvothermal method for 16 h, exhibited a minimum reflection loss (RL_min) of −66.44 dB at a thickness of 2.29 mm. When the thickness was reduced to 1.50 mm, the optimal effective absorption bandwidth was 3.84 GHz. Analysis of the absorption mechanism of FNC/RGO/MDCF revealed that its excellent absorption performance was primarily attributed to the combined effects of conduction loss, multiple reflection, scattering, interface polarization, and dipole polarization.