Background: Today, the valorization of wastes and residues is important to follow the guidelines of sustainable development.Objective: The objective of the work was to maximize the mechanical performances while reducing the costs. Method: In this work, optimization of the mechanical properties (tension, flexion and impact) for a composite system containing high density polyethylene as the matrix, hemp fibers as reinforcement, ground tire rubber as an impact modifier, and maleic anhydride grafted polyethylene as a coupling agent was performed. The compounds were produced by twin-screw extrusion and molded via injection. Results: From the results obtained, a quality/cost ratio optimization was done to determine the best composite formulation. Conclusion: Overall, it was found that the best composition was around 30% hemp with 30% ground tire rubber as this composition represent a good balance between strength and toughness.