In recent years there has been a heightened concentration on the industrial subsectors that are the primary contributors to environmental pollution. Filler materials made from mineral limestone, which is composed of calcium carbonate (CaCO3), are utilized in the production of polymer composites in order to lower production costs and improve the qualities of some of the composites. On the other hand, eggshells are typically regarded as waste despite the fact that they contain significant amounts of CaCO3 in addition to certain organic membranes. The purpose of this research is to investigate the use of thermal and chemical treatments to produce purified eggshell powder with the interest of utilizing waste eggshell as an alternative to limestone. Polymer composites were developed using bio-epoxy resin with various quantities of eggshell, refined eggshell, and limestone fillers (5%, 10%, and 20% weight). Eggshell could be utilized as filler in bio-epoxy composites, which could then be employed in applications that require a lower cost but a greater tensile and flexural modulus.