Three-dimensional (3D) hierarchical structures have been widely employed to enhance the microwave absorption performance due to their large surface area, satisfied impedance matching and polymorphic morphology. However, to achieve multiphase and multifunctional performance only within a primary unit remains a tremendous challenge. Herein, special carbon-based C/MoO₂/Co₃O₄ nanosheets were assembled into a flower-like hierarchical architecture by a facile coordination-polymerization method. Abundant Co₃O₄ magnetic nanoparticles were anchored onto carbon nanoflake substrates, leading to both enhanced polarization and enhanced magnetic coupling. Meanwhile, a large number of heterogeneous junction interfaces among MoO₂ nanoparticles and carbon substrates enhanced the interface polarization. Therefore, the C/MoO₂/Co₃O₄ microflower achieved a minimum reflection loss of −59.7 dB at 17.7 GHz with a thickness of only 1.2 mm, indicative of its great potential as a lightweight microwave absorption material.