In this work, we report the first synthesis of photochromic aerogels and films based on TEMPO-oxidized cellulose and chitosan modified with tungsten trioxide nanoparticles. The blue coloring of aerogels based on WO3-modified biopolymers under UV light occurs due to the reduction of W+6 to W+5. The coloration of films of the same composition occurs due to the reduction of W+6 to W+5 and W+4. The photochromic properties of aerogels and films are reversible; oxidation by atmospheric oxygen leads to bleaching of materials. At that, films become colorless within a few days while aerogels with a high specific surface area (200 m2/g) become colorless within several minutes. The antioxidant properties of the WO3 sol and the WO3/TEMPO-oxidized cellulose/chitosan composite were studied by luminol-activated chemiluminescence method. The antioxidant capacity of WO3/TEMPO-oxidized cellulose/chitosan gel is 1.5 times higher than that of the commercially available antioxidant mexidol.