A green photoinduced method for the modification of a biodegradable and biocompatible polymer, Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) has been successfully carried out using two types of monomers with potential antibacterial effects, i.e. 2-[(methacryloyloxy)-ethyl] trimethylammonium chloride (META) and an ampicillin-derived monomer. The photografting process is conducted through a photoinduced free-radical process employing a thiocarbamate-based photoinitiator in an aqueous medium. Under appropriate conditions, radicals are generated from the PHBHV surface, thus initiating the UV-mediated photopolymerization of methacrylate or methylacrylamide-derived monomers from the surface of PHBHV films. The photochemical mechanism of the thiocarbamate photolysis is entirely described by the Electron Spin Resonance / Spin-Trapping technique and Laser Flash Photolysis, and the modified-PHBHV films are extensively characterized by fluorescence experiments, water contact angle and XPS measurements. Finally, a primary investigation is conducted to support the antibacterial property of the new functionalized films against Escherichia coli and Staphylococcus aureus, and their cytocompatibility with NIH-3T3 fibroblastic cells is evaluated.