In the current research, a chitosan/broccoli extract/ZnO nanoparticle (CH/BE/ZnO) bionanocomposite was created. The physicochemical properties of CH/BE/ZnO bionanocomposite were investigated using a variety of methods, including field emission scanning electron microscopy (FESEM), elemental analysis (CHN-O), X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), Brunauer-Emmett-Teller (BET), and transmission electron microscopy (TEM). The CH/BE/ZnO bionanocomposite's biological activity was assessed by examining its cytotoxicity capabilities against a bone cancer cell line (MG63). The total pore volume and specific surface area of CH/BE/ZnO are 0.134 cm 3 /g and 16.99 m 2 /g, respectively. The IC50 results for CH/BE/ZnO bionanocomposite in bone cancer investigations using the MTT test against the MG63 cell line was 115 μg/mL. The results indicate that the CH/BE/ZnO bionanocomposite is an effective chemotherapeutic agent against human osteosarcoma. The CH/BE/ZnO bionanocomposite showed high performance and structure, which means innovating nanomaterial agents for biological applications in the future., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)