Fiber-reinforced composites that integrate efficient and broadband electromagnetic wave (EMW) absorption with structural load-bearing capability have attracted considerable attention for radar-stealth applications. However, achieving effective absorption in the low-frequency band (< 8 GHz) remains challenging for dielectric-loss-dominated absorbers due to the long wavelength, which hinders the simultaneous realization of impedance matching and sufficient attenuation. Herein, we propose a SiC_f/GF hybrid woven metacomposite, in which EMW-transparent glass fiber (GF) is hybrid woven with dielectric loss silicon carbide fiber (SiC_f) to construct metastructural units compatible with large wavelengths, thereby extending the absorption performance towards the low-frequency regime. A genetic algorithm (GA) is integrated with full-wave simulations to optimize the fiber ratio, weaving pattern, and thickness of the hybrid woven metacomposite. Simulation results indicate that the optimized structure exhibits a reflection loss (RL) below −10 dB across the 4–15.6 GHz range, while experimental measurements confirm consistent broadband absorption from 4 to 12.5 GHz. The enhanced EMW absorption performance is attributed to the hybrid woven metacomposite, which facilitates deep wave penetration and efficient energy dissipation through synergistic impedance matching and multi-mechanism loss. Overall, this work presents a systematic strategy for developing low-frequency broadband structural microwave absorbers, with promising applications in electromagnetic shielding, radar stealth, and advanced electromagnetic protection.