Developing lightweight electromagnetic wave absorbers with low filler loading remains challenging. However, carbon materials rarely achieve strong attenuation capability, wide absorption bandwidth, lightweight and thin thickness simultaneously. Herein, a carbon fiber-hyperbranched polyamide-reduced graphene oxide (CF-HP-RGO) interfacial micro-capacitor architecture was rationally constructed through thermal reduction. The incorporation of HP and RGO introduces dual heterogeneous interfaces between carbon fibers and RGO layers, while forming CF-HP-RGO micro-capacitor units that act as dominant polarization centers. Under alternating electromagnetic fields, these micro-capacitor interfaces generate pronounced charge accumulation and interfacial polarization, thereby strengthening dielectric relaxation and polarization loss. Meanwhile, the interconnected RGO network establishes efficient electron-transport pathways, producing additional conductive loss. In addition, the multilayer hierarchical interface enhances multiple scattering, effectively extending electromagnetic propagation paths and improving attenuation efficiency. As a result, the optimized composite delivers a maximum effective absorption bandwidth of 5.24 GHz in the Ku band at an ultrathin thickness of 1.6 mm with a filler loading of only 5 wt.%. This work highlights micro-capacitor-dominated interfacial engineering as a promising route toward lightweight and high-performance electromagnetic wave absorption in carbon materials.