Biopolymer-mediated sonochemical synthesis has been carried out for obtaining stable, nanocrystalline ZnO-biopolymer nanocomposite colloids to be applied on polymer foam and cotton fabrics to ultimately produce multifunctional, heath-care surface modifications. In situ nucleation and growth of nano-ZnO was achieved by ultrasonication at ∼ 60°C in aqueous biopolymer media prepared using starch, gelatin, chitosan, and agar. Phase analysis, structure-bonding characteristics, ZnO morphology, particle size distributions, rheology, and thermal decompositions were studied using XRD, FTIR, SEM/TEM, viscometer, and TG/DTA tools. Morphologically varied nanocrystalline ZnO of size ∼ 40 nm were synthesized. Biopolymers media resulted in stable ZnO colloids through steric stabilization. ZnO-biopolymer nanocomposites colloid was applied on polyurethane foams and cotton fabric substrates by dip coating. These coatings were examined for the UV photoactivity and resistance to fungi growth. A comparison has been made among the biopolymers. It is shown that the surface coatings of ZnO-biopolymer nanocomposites can produce anti-fungal, UV active polymer foams and fabrics. The study has significant relevance in automobile and hospital industries because such functionally modified polymer foams and cotton fabrics can be disinfected and refreshed just by periodic application of water-free, UV cleaning.