Biosynthesis of nanoparticles is an interdisciplinary application of metal science and technology through biology. SeNPs can be used for various applications especially in medicine, due to its medicinal properties such as low toxicity, better reactivity, low dosage, etc. Medical applications include drug targeting, drug discovery, diagnosis and regenerative medicines. When applying nanotechnology to medical uses, it is particularly important to ensure thorough safety evaluation of any new technologies and also to review the likely environmental impact. Due to the increasing number of antibiotics employment of SeNPs as antimicrobial agents has been widely investigated. The most common mechanism of action of SeNPs is the attachment of particles to the bacterial surface and release of the selenium ions into the bacterial cell, which generally causes the oxidation stress, inhibition of protein synthesis or DNA mutation. SeNPs were developed to treat S. aureus infections. Although there are previous reports on the biosynthesis of SeNPs using plant extract and microorganisms are available, the enhanced antibacterial activity of arrowroot mediated selenium nanoparticles is new to the field of nanotechnology. Arrowroot mediated Zinc oxide nanoparticles were initially synthesised and characterised by UV-Visible spectrophotometer and TEM. The enhanced antibacterial was studied by inoculating it in the culture media. The results showed that Arrowroot mediated selenium nanoparticles showed good antibacterial activity. An increased bacterial zone of inhibitions was observed against both Streptococcus mutans and Lactobacillus. Thus arrowroot mediated SeNPs can be used as an antibacterial agent.