<p>Electromagnetic technologies have been widely applied in various fields including industry, digital economy, and emerging domains such as 5G and IoT. However, this has led to a dramatic increase in electromagnetic energy in free space, posing threats to human health, electronic device operation, and national defense security. So, traditional electromagnetic functional materials struggle to adapt to complex electromagnetic environments due to their narrow absorption bandwidth and single functionality. Without doubt, the development of multi-band electromagnetic absorbing materials has become imperative. Reduced graphene oxide (rGO) exhibit unique advantages in electromagnetic wave absorption, including high specific surface area, polarization relaxation effects, and tunable conductivity. RGO can serve either as an independent absorber or as a modifier to enhance the performance of traditional absorbing materials, making it a promising candidate for multi-band electromagnetic wave absorption. In this manuscript, we fabricated an rGO aerogel that demonstrates excellent electromagnetic wave absorption (EWA) performance in both gigahertz (GHz) and terahertz (THz) bands. In the GHz range, it achieves a maximum effective absorption bandwidth of 6.74&#xa0;GHz and a peak absorption intensity of -67.3&#xa0;dB. Its absorption performance in the THz band (0.2–2.2 THz) is also outstanding, and effective absorption cover the whole frequency range. Furthermore, software simulations were employed to evaluate electromagnetic countermeasure capabilities of rGO in real-world scenarios. The results indicate a significant reduction in the target’s radar cross-section (RCS) after coating with the absorber, with the average RCS (RCS_av) decreasing from -14.27 dBm² to -29 dBm², a 103% improvement in electromagnetic absorption capability.</p>