 This study investigated the use of a new type of polymer-based composite membrane structure to create high-performance microwave absorbers. The structure was composed of one-dimensional end-oped carbon nanofibers embedded within HoloCo3-SNC0.7 nanocubes. The presence of space charge stacking between the nanoparticles allowed for the formation of a necklace structure, which could then be further enhanced by the presence of a carbon network. This combination of factors resulted in a high impedance matching and a large absorption bandwidth. When tested at 800 degrees Celsius, the necklace-like structure exhibited an RL value of minus 51.2 dB at 2.3 mm and a thickness of 2.5 mm. Furthermore, the multiple reflections and interfacial polarization between the fibers and their internal walls contributed significantly to the overall absorption of electromagnetic waves.