A series of spirocyclopropyl oxindoles with benzimidazole substitutions was synthesized and tested for their cytotoxicity against selected human cancer cells. Most of the molecules exhibited significant antiproliferative activity with compound 12p being the most potent. It exhibited significant cytotoxicity against MCF-7 breast cancer cells (IC50 value 3.14 ± 0.50 µM), evidenced by the decrease in viable cells and increased apoptotic features during phase contrast microscopy, AO/EB, DAPI and DCFDA staining studies. Compound 12p also inhibited cell migration in wound healing assay. Anticancer potential of 12p was proved by the inhibition of tubulin polymerization with IC50 of 5.64 ± 0.15 µM. These results imply the potential of benzimidazole substituted spirocyclopropyl oxindoles, notably 12p, as cytotoxic agent for the treatment of breast cancer.