Microwave absorption materials are prone to degradation in extremely humid and salty environments, and it is still challenging to develop a dense and firm interface to protect microwave absorbers. Herein, a robust FeSiAl@PUA@SiO₂ (PUA: acrylic polyurethane) gradient hybrid was prepared through plasma-enhanced chemical vapor deposition (PECVD) to achieve efficient microwave absorption and anti-corrosion properties. The organic/inorganic dual coat of PUA/SiO₂ not only facilitated the interface polarization but also effectively reduced the dielectric constant and optimized impedance matching. Owing to the unique hybrid structure, the (PECVD-FeSiAl@PUA)@SiO₂ exhibited highly efficient microwave absorbing performance in frequency bands covering almost the entire Ku-bands (12–18 GHz) with a minimum reflection loss (RL_min) of −47 dB with a matching thickness of 2.3 mm. The organic/inorganic dual protection effectively shields against the corrosive medium, as the corrosion potential and the polarization resistance increased from −0.167 to −0.047 V and 8,064 to 16,273 Ω·cm², respectively. While the corrosion current decreased from 3.04 × 10⁻⁶ to 2.16 × 10⁻⁶ A/cm². Hence, the plasma-enhanced densification of PUA created a strong bridge to integrate FeSiAl and organic/inorganic components acquiring dual-function of efficient microwave absorption and anti-corrosion, which opened a promising platform for potential practical absorbers.