In this study, we formulated an oil-in-water nanoemulsion of Citrullus lanatus seed oil in the presence of Phyllanthus niruri methanolic extract using a delivery system based on sodium alginate. The control nanoemulsion was prepared without plant extract and the nanoemulsion loaded with extract was further characterized based on their size, polydispersity index, morphology, and stability. The nanoemulsion showed an average droplet size of about 192 nm, with a polydisperse droplet size with a spherical shape and the zeta potential of -15.0 mV and -18.4 mV. In contrast to the control nanoemulsion, the drug release rate of the nanoemulsion formulation was found to be significant (p <0.05). Antibacterial activity was assessed against a variety of pathogenic bacterial and fungal strains and the formulated nanoemulsion exhibited significantly higher potency against them in comparison to P. niruri extract alone. The results revealed thermodynamically stable nanoemulsion which could be used for various therapeutic applications