Plant-derived compounds have recently garnered significant interest in the field of medicine due to their rich repertoire of phytochemicals, which holds promise for exploring novel therapies to treat cancer. This study embarks on the first-time investigation of the anti-cancerous effect of onion-derived nanovesicles (ODNVs). ODNVs were isolated employing differential centrifugation followed by ultracentrifugation and subsequent characterization using dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR). Furthermore, we delineated the anti-cancerous effect of ODNVs on two cancer cell line models HeLa (cervical cancer) and PC-3 (prostate cancer) using MTT assay, DAPI-based DNA damage using immunofluorescence microscopy, colony formation assay, migration assay, cell cycle analysis, and evaluation of apoptosis using flow cytometry and western blotting. The findings revealed dose- and time-dependent anti-proliferative effects of ODNVs on both HeLa and PC3 cell lines, accompanied by selective cytotoxicity against cancer cells. Additional results highlighted that ODNVs prevented colony growth and induced S-phase cell cycle arrest. Apoptosis induction was evaluated through alterations in nuclear morphology and the number of apoptotic cells, which increased significantly after ODNV treatment in both cancer cell lines. Furthermore, annexin V/PI staining evaluation of apoptotic cells by flow cytometry demonstrated that ODNV treatment significantly increased the number of apoptotic cells in both PC-3 and HeLa cells. Finally, Western blot analysis indicated changes in apoptosis-related proteins including bcl-2, bax, and caspase-3, emphasizing that the anti-cancerous effect of ODNVs is attributed to the induction of apoptosis and suggests the unexplored anti-cancerous potential of ODNVs.