Abstract The present investigation aimed to produce ecological composites of biopolyethylene (BioPE) with macaíba shell (MS), using polyethylene‐graft‐maleic anhydride (PE‐g‐MA) and polyethylene‐graft‐acrylic acid (PE‐g‐AA) as compatibilizers, as well as macaíba almond oil as a plasticizing agent. The composites were processed in a co‐rotational twin‐screw extruder and injection molded. The addition of 30% by weight of MS in the BioPE matrix caused a reduction in impact strength and elongation at break, but improved stiffness and heat deflection temperature. The PE‐g‐MA and PE‐g‐AA compatibilizers improved the impact strength of the composites, suggesting increased interactions between the phases. There was an increase in the composites degree of crystallinity, indicating that the MS acted as a nucleating agent. The macaíba oil addition to the composites increased the impact strength, indicating a plasticizing effect. However, the elastic modulus, tensile strength, and degree of crystallinity tended to decrease. In general, the use of PE‐g‐MA compatibilizer was more effective to improve the composites mechanical properties. The reuse of MS is feasible for the production of sustainable composites.