<p>Agricultural production brings along huge amounts of agro-industrial waste, result in environmental problems such as storage and disposal. Today, it is crucial to use waste as a source of raw materials in order to reduce environmental pollution, promote a circular economy, and support sustainable waste management. Biocomposite materials are one of the important approaches to sustainable waste management. Natural fibre reinforcements have been attracted attention in the development of biocomposites due to their biodegradability and renewability. In the study, waste walnut shells were ground in the range of −154/+77 μm so they were used as a reinforcing element. The micro powders were mixed with bio-resin at different rates (2%, 4%, 6%, 8%) to produce a biocomposite material. Tensile, three-point bending, izod impact and hardness tests were run to determine the mechanical properties of the biocomposite materials. Moreover, water absorption test, thermogravimetric analysis (TGA), differential thermal analysis (DTA) and SEM analysis were performed on the biocomposite samples. The highest tensile strength was obtained in biocomposite materials produced by adding 2% waste walnut shell powder. When the modulus of elasticity of all biocomposites was compared with the base material (BM), increases of approximately 100% were determined. As rate of the reinforcing element increased in biocomposite materials, micro powders agglomerated in the matrix.</p>