The development of radar stealth for high‐speed flight vehicles and aviation engines requires novel flexible fiber materials that can not only withstand high temperatures, but also exhibit superior electromagnetic wave absorption. This study addresses this challenge by reporting the successful fabrication of submicron‐diameter (≈700 nm) SiC fibers with excellent properties. These fibers achieve the best electromagnetic wave absorption performance (−63.34 dB) among all the ceramic fibers, maintaining high‐temperature stability up to 1800 °C. They also demonstrate excellent oxidation resistance (1400 °C) and thermal insulation (0.273 W m−1 K−1 at 1200 °C). Furthermore, the fibers exhibit excellent corrosion resistance, prominent hydrophobic properties, reliable filtering quality, and excellent flexibility. This study overcomes the limitations of conventional multifunctional micro/nanofibers by achieving superior high‐temperature performance and electromagnetic absorption. These SiC fibers are promising materials for structural and functional integration in extreme environments.