The increasing resistance of pathogens and cancer cells to antibiotics and anticancer drugs has sparked the discovery of novel therapeutic materials. Recently, the utilization of plant compounds and byproducts in nanomaterials fabrications has great attention in biomedicine and bioremediation. In this work, almond gum coated MgO nanoparticles were synthesized by a simple green synthesis method. The physicochemical properties of prepared nanoparticles were systematically evaluated using various microscopic and spectroscopy techniques. The biological potential of AG@MgO nanoparticles was evaluated against human infectious pathogens, (Streptococcus pneumoniae, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae). The anticancer potential of nanoparticles was assessed against MCF-7 a breast cancer cell which shows excellent cell damage in the lowest concentration. The larvicidal potential of nanoparticles was evaluated against Aedes aegypti mosquito larvae, the mortality rate of larvae increases as the concentration ratio of AG@MgO nanoparticles increases. The final results concluded that the AG@MgO nanoparticles efficiently control bacterial, breast cancer cell growth, and mosquito larvae.