This paper aims to investigate the mechanical properties of bio-composites reinforced with basalt natural fibers/nanographene in polypropylene by incorporating pp-g-ma compatibilizer. The study employs the Response Surface Method with the Behnken box approach to formulate a novel mathematical model for bio-composite behavior based on the parameters of basalt fiber weight percentage, nanographene weight percentage, and PP-g-MA weight percentage. Unlike previous studies, our work uniquely integrates basalt fibers and nanographene to enhance tensile, bending, and impact strengths, achieving a composite with optimal mechanical properties. The performance of the research samples was evaluated through tensile, bending, and impact tests, with the results substantiated using Field Emission Scanning Electron Microscopy images. The failure surface in these samples revealed that the central mechanism influencing the performance of the introduced bio-composite is the failure of the fibers and their separation, accompanied by the stretching of the fibers from the base material. Subsequently, multi-objective optimization was conducted with the aim of increasing tensile strength, bending strength, and impact strength while reducing the weight of the samples. A Pareto diagram is presented based on the design goals. The outcomes indicate that the bio-composite sample values in the most suitable state for three mechanical characteristics including, tensile, impact, and bending strength are equal to 28, 90, and 49 MPa, respectively. This innovative combination and optimization significantly improve performance metrics, demonstrated through extensive testing and multi-objective optimization, which reveals the bio-composite's superior mechanical characteristics.