<p>This study explores the synthesis and dynamic performance of polylactic acid (PLA) composites reinforced with bio-fibers, specifically jute and flax, combined with particulate fillers such as coconut shell and eggshell powder. The objective is to evaluate the viability of these composites as eco-friendly alternatives to conventional synthetic materials in structural applications. Through a series of mechanical tests, including tensile, flexural, impact, hardness, creep, and fatigue assessments, the enhanced mechanical properties and long-term durability of the reinforced PLA composites are demonstrated. Results indicate that jute-reinforced composites, particularly those containing eggshell or coconut shell powder, exhibit superior tensile strength, hardness, and impact resistance, making them suitable for applications requiring both strength and toughness. Flax-reinforced composites provide a balance of strength and flexibility, while the inclusion of particulate fillers improves stiffness and durability. Creep and fatigue testing further reveal that jute and flax composites exhibit enhanced resistance to long-term deformation and cyclic loading, with the JPC (jute/PLA/coconut shell powder) composite showing exceptional performance. Among the composites, the JPC composite (jute/PLA/coconut shell powder) had the maximum surface roughness of 0.074, while the FPE composite (flax/PLA/eggshell powder) had the least roughness value of 0.0038. The JPC composite (jute/PLA/coconut shell powder) demonstrated the highest hardness score of 99 Shore D, and the JPE composite (jute/PLA/eggshell powder) also scored relatively high at 97 Shore D. These findings suggest that natural fiber-reinforced PLA composites offer a sustainable, cost-effective solution for industries seeking materials with both environmental and mechanical benefits. Future research should focus on optimizing fiber-matrix interactions to enhance the performance of these composites in demanding applications.</p>