This study aims to develop sustainable polyester hybrid composites by incorporating environmentally friendly fillers such as pistachio shell and talc into an orthophthalic polyester matrix. The goal is to produce cost-effective, eco-friendly materials for applications such as exterior cladding and electronic enclosures. The mechanical (tensile, flexural, impact), thermal (FT-IR, TGA, DSC), and physical (water absorption, hardness, density, gloss) properties of the prepared composites were tested. Pure polyester exhibited the highest tensile strength at approximately 50 MPa, while the addition of 40% pistachio shell reduced the mechanical properties by 69%. In contrast, the addition of talc increased the tensile strength by 55% compared to the composite with only pistachio shell. Talc also improved thermal stability (increasing the T5 temperature by 7% and Tmax by 2%) and reduced water absorption by 4%. The combination of both fillers optimized the material properties, providing a sustainable and high-performance alternative. These findings suggest that further optimization of filler content could improve performance and expand material applications.