A novel method for the preparation of composites based on poly(vinyl alcohol) (PVA) and micro- and nano-fibrillated cellulose (M/NFC) is reported. The addition of crosslinking HEMA monomers and a photo-initiator enabled the formation of an interpenetrated polymer network that displayed enhanced interfacial adhesion and dispersion of (M/NFC) in the matrix. Photo-crosslinked PVA/(M/NFC)/polyHEMA composite films produced by casting followed by UV polymerization of HEMA were characterized by using several approaches. These included Fourier transform infrared and UV–Vis spectroscopies, differential scanning calorimetry, X-ray diffractometry, thermogravimetric analysis and dynamic mechanical analysis. The thermo-mechanical and optical properties as well as water absorption and vapor barrier abilities of the developed photo-crosslinked PVA/(M/NFC)/polyHEMA films were measured and the benefit of photo-crosslinking determined. The major degradation peak of photo-crosslinked PVA/(M/NFC)/polyHEMA composites increased substantially compared to that of the PVA/(M/NFC) system (from ~300 to ~350 °C). The water vapor permeability of PVA/(M/NFC)/polyHEMA composite films was reduced with HEMA loading (5.44 × 10−11, 5.10 × 10−11, 4.12 × 10−11, 4.31 × 10−11 g/m h Pa for 0, 5, 10 and 15 % HEMA, respectively). Overall, a new and facile method for the synthesis of PVA/(M/NFC)-based composite networks interpenetrated with cross-linked poly(HEMA) is demonstrated, offering excellent prospects for packaging applications.