In the present report, we provide the results of the molecular biology studies of spiroheterocyclic hybrids, where the derivatives are found to possess potential anticancer activity towards cancer cells. A series of spiroxindole−pyrrolidine heterocyclic hybrids were evaluated for cell viability and proliferation against HepG2 cancer cells at concentrations in the range of 12.5−200 µg/mL over two different time periods of 24 and 48 h. In addition, the highly active compounds were also verified for their behavior towards noncancer cells (L929 cells), and it was found that the tested derivatives were not aggressive due to the observation of only limited cell loss, as compared to the cancer cells. Further analysis of the observed toxicity mechanism showed the apoptotic pathway was mediated by oxidative stress, with the involvement of caspases.