Surface modification of inorganic metal oxide nanoparticles with organic biopolymers has endowed these particles with multifunctional properties, making them versatile in the field of nanomedicine. In the present study, magnesium oxide and chitosan modified magnesium oxide is synthesised by green method. Amomum subulatum Roxb is used as a nucleating agent. Various characteristic techniques used on the synthesized hybrid nanomaterial demonstrated that the antibacterial and anticancer activities are attributed to the generated reactive oxygen species. The antibacterial activity exhibited appreciable efficacy of chitosan modified magnesium oxide hybrid nanomaterial against the tested bacterial strains compared to its counter parts. The zone of inhibition was in the range of 12-23 mm. Additionally, the anticancer potential was evaluated against human breast cancer cells, showing a significant effect for chitosan modified magnesium oxide hybrid nanomaterial with half-maximal inhibitory concentration of 35 μg/mL and 40 μg/mL for MgO. Cytotoxicity assays conducted on the human fibroblast L929 cell line revealed a cell viability rate of 80% and 87% for magnesium oxide and chitosan modified magnesium oxide hybrid nanomaterial. Overall, these findings indicate that chitosan modified magnesium oxide hybrid nanomaterial holds promise for applications in the biomedical field.