AbstractLightweight and strong microwave adsorption property have become the foremost crucial factors in the practical application of modern microwave absorbers. This study mainly dealt with synthesize of bamboo‐like β‐SiC nanowires with high‐performance microwave absorption property via a polymer pyrolysis CVD (PPCVD) approach. The PPCVD process was conducted by cleverly placing the polymer powders into two temperature zones to produce reactant gases with alternating concentrations. The morphological study revealed that the nodes exhibited abundant stacking faults as compared to the stem segments, which was beneficial for the microwave losses. The optimal reflection loss value of −35.47 dB was gained at 18 GHz corresponding to 2.0‐mm absorber thickness, and the corresponding −10 dB bandwidth (>90% absorption) was 3.22 GHz. It has turned out that the as‐prepared nanowires could be applied at different frequencies by adjusting the thickness. Especially, it exhibits a good prospect in the fields of ultrathin absorbers. Furthermore, the microwave absorption mechanisms of the nanowires were explored. This present investigation has opened a high‐efficient facile approach to develop ultrathin, lightweight, and high‐performance microwave absorbers.