Mahanimbine is a carbazole alkaloid that has been identified and isolated from several members of the Rutaceae family. Previous studies have demonstrated that alkaloids such as mahanimbine exhibit the capacity to suppress the growth and progression of cancer cells. Therapeutic side effects and the cost of management for patients with lung carcinomas demand the exploration of natural plant-based therapeutic options for this debilitating disease. The study was focused on elucidating the mechanism of inhibition of non-small-lung cancer A549 cells post exposure to mahanimbine. The preliminary investigation was centered on evaluating the cytotoxic effects of mahanimbine on A549 cells along with the exploration of pathways resulting in growth inhibition of A549 cells. Our results showed that mahanimbine restrained the growth of non-small lung cancer A549 cells substantially by activating reactive oxygen species-dependent intrinsic apoptotic pathways. Therefore, this initial study indicated that mahanimbine serves as a plausible anti-cancer therapeutical option for the treatment and management of lung cancer.