Herein, we report (polystyrene-co-polymethylmethacrylate/silver/reduced graphene oxide)-(nano-hydroxyapatite) ((PS-PMMA/Ag/RGO)-(nHA)) nanocomposites as potential bone cement. The polymer nanocomposites were characterized using Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction (XRD), nano-indentation, thermal, and electron microscopic methods. The FT-IR and XRD results confirmed the successful formation of the nanocomposites. The elastic modulus (E) was found to be 6.85 GPa, and hardness (H) was 0.181 GPa for the nanocomposite bone cement samples, while the E and H values of commercial counterparts are 7.22 and 0.218 GPa, respectively. The thermogravimetric analysis (TGA) has revealed that the nanocomposite bone cement are stable up to 371 °C. The addition of nHA enhances the biocompatibility of bone cement. Cytotoxicity studies were conducted using human osteosarcoma MG63 cell lines. In-vitro studies showed that the material does not display any toxicity on the MG63 cell line, and increased concentration of nHA did not significantly impact the material’s toxicity, only impacting the curing kinetics of the cement.