A facile approach for adding moisture resistance to transparent nematic aerogels composed of individualized cellulose nanofibers (i-CNF) at full preservation of the anisotropic aerogel structure is presented. Sequential nitroxide-mediated oxidation and mechanical cellulose fiber delamination were applied to obtain i-CNF dispersions in water. Nematic ordering caused by repulsive forces between i-CNF surface carboxylate groups was set by acid-induced hydrogen bonding and gelation, respectively. Solvent exchange to acetone, impregnation with the PMMA, scCO2-mediated antisolvent precipitation of the secondary polymer, and scCO2 extraction of interstitial acetone afforded highly hydrophobic nanocomposite aerogels. Birefringence studies utilizing polarized light and the Michel–Levy Chart to evaluate interference patterns revealed that nematic i-CNF ordering is virtually not affected by the respective surface modification and scCO2 drying steps. Morphological studies provide evidence that the large internal surface (>500 m2 g–1) of the hybrid aerogels consists of a homogeneous ultrathin PMMA (mono)layer that virtually does not affect the high porosity (≥99%) and transparency (>77% transmission, 600 nm, 2.13 mm thickness) inherent to i-CNF aerogels. The obtained materials exhibited excellent resistance toward moisture as apparent from the high water contact angle (119.4° ± 7.5). As PMMA imparts the aerogel stiffness and hydrophobicity, aggregation of nanofibrils in moist environment or under vacuum conditions can be avoided even at ultralow densities as low as 9.6 mg cm–3.