<p>This study aims to evaluate the environmental sustainability of biocomposites produced from chestnut waste by examining their biodegradability, phytotoxicity, and life cycle impacts under realistic end-of-life scenarios. Addressing key gaps in current research, it provides a comprehensive assessment of the potential of non-commercial chestnut residues as feedstocks for small decorative indoor products within a circular bioeconomy concept. Degradability was assessed through soil-burial tests over 120 days, while phytotoxicity was evaluated using seed germination and growth assays across six plant species. A cradle-to-grave Life Cycle Assessment (LCA), covering 18 environmental impact categories, was conducted for different formulations, considering the presence or absence of plasticizing (glycerol) and hydrophobic (shellac) agents, as well as alternative end-of-life scenarios, including landfill and composting. Additionally, a scale-up scenario for the most environmentally favorable biocomposite was modeled and compared with an equivalent fossil-based polyethylene product, including energy recovery through incineration at end of life. Both biocomposite (with and without shellac) formulations exhibited rapid and complete degradation within 120 days, with no significant effect of shellac. Germination rates generally remained above 60%, indicating low phytotoxicity, although root and shoot growth were more sensitive, particularly in shellac-containing samples. LCA results identified the additive-free composite with composting as the most environmentally favourable option, while landfill increased toxicity-related impacts. Production processes, especially moulding and packaging, were the main contributors to environmental burdens. Overall, chestnut residues can be effectively valorised into degradable, low-toxicity biocomposites with competitive environmental performance, offering a promising complementary pathway within circular systems.</p> Graphical Abstract <p></p>