Abstract: To address the challenges of poor impedance matching and the difficulty in balancing lightweight with multi-functional integration in traditional carbon-based microwave absorption materials, nanocellulose-derived carbon aerogels (NCA) were successfully prepared by constructing a three-dimensional (3D) conductive network using hollow carbon spheres (HCS) and cellulose nanofibers (CNF) via an ice-templating method followed by high-temperature carbonization. Benefiting from the synergistic effect of the unique hollow structure of HCS and the porous network of CNF, the material forms abundant dielectric loss mechanisms. The results indicate that the composite aerogels exhibit an ultralow density of only 14.25 mg/cm³. When the carbonization temperature is 600℃, the prepared NCA composite achieves a minimum reflection loss (RL_min) of −64.85 dB at a matching thickness of 2.9 mm, and the effective absorption bandwidth (EAB) reaches 5.60 GHz at a matching thickness of 1.9 mm. Furthermore, the radar cross section (RCS) is significantly reduced by 16.50 dB·m² at a detection angle of 0°. Meanwhile, infrared thermal imaging tests confirm the superior infrared stealth and thermal insulation performance of the composite aerogels. The surface temperature remains around 114℃ even after heating on a 300℃ hot plate for 1 h. This work effectively solves the impedance mismatch problem of single-component carbon materials. It achieves radar-infrared compatible stealth while realizing lightweight properties. This provides a theoretical basis and technical support for the development of novel multifunctional electromagnetic protection materials.