Abstract: The naproxen ligand was employed to build several complexes via its interaction with metal ions (Co(II) and Zn(II)). The structures of these novel compounds were examined in both solid and solution phases utilizing several spectroscopic techniques, including UV-Vis, FTIR, and elemental studies, all performed at ambient temperature. The naproxen complexes coordinate with metal ions through the carbonyl oxygen of their carboxyl groups. The chemical formulae of the produced complexes reveal that the CoL complex has octahedral geometry, whereas the ZnL complex indicates tetrahedral geometry. The MTT assay evaluated the cytotoxicity and viability of MDA231 cell lines following 48 hours of exposure to various doses (400, 200, 100, 50, and 25 µg/ml) of the chemicals. The MTT assay results demonstrated substantial inhibition rates for all ligands and their metal complexes at different dosages, in comparison to cisplatin, which acted as the positive control.