The current trend in deteriorating mechanical performance of green polymeric-based materials has made it essential for designers to establish more reliable and sustainable bio-products. Here, the mechanical performance of Jordanian lignocellulosic olive fibers in polymeric-based composites has been methodically investigated. The outcomes of different reinforcement conditions on the desired mechanical performance of the olive leaf’s lignocellulosic fibers with low-density polyethylene (LDPE) composites have been examined, including the properties of tensile strength, tensile modulus, mechanical strain, impact strength, and the intensity per composite volume. This has been accomplished to determine the optimum reinforcement condition for the desired mechanical behavior as well as to establish the performance deterioration and enhancement trends of such bio-materials in a more consistent manner. The results signify that lignocellulosic olive fibers have exhibited various enhancements in terms of mechanical performance. Both the tensile strength and modulus of elasticity have been dramatically improved at 20 wt.% fiber content. This was the most desired reinforcement condition among all considered cases. The olive fibers also possess the capability of maintaining relatively high ductility and impact strength properties, making them suitable for various industrial applications where high ductility is necessary. Thermal stability analysis using TGA and DTG has been employed to obtain accurate results.