Garcinia celebica (G. celebica), an aromatic plant which is domestically planted for fruits and ornamental purposes, is exceptionally rich in important phytochemicals that may contribute to its medicinal properties. The mechanistic basis of cytotoxic action of G. celebica essential oil (EO-GC) in MCF-7, MCF-7/TAMR-1, and MCF-10A cell cultures was explored in this study. The study findings showed that the EO-GC potently inhibited the proliferation of the MCF-7 and MCF-7/TAMR-1 cells by 50% at 37.5 µg/mL and 18.8 µg/mL concentrations, respectively. In contrast, a higher concentration (77.5 µg/mL) of the essential oil was needed to inhibit the MCF-10A cells. These findings demonstrated that the EO-GC possesses selective cytotoxic effects by two-fold and four-fold towards the MCF-7 and MCF-7/TAMR-1 cells, respectively, than the MCF-10A cells. Flow cytometric analysis has proven that the EO-GC can effectively induce apoptotic cell death in the cultured MCF-7 and MCF-7/TAMR-1 cells, while having minimal effect on the MCF-10A cells. Therefore, these preliminary findings may add novel scientific data related to the potential therapeutic efficacy of the ethereal oil derived from G. celebica leaves.