Green synthesis of nanoparticles has evolved as an ecologically friendly and sustainable method for producing nanoparticles using natural sources like botanical extracts. Withania somnifera, commonly known as ashwagandha, is a medicinal plant known for its diverse therapeutic properties. This work focuses on the green synthesis, characterization, and applications of selenium nanoparticles (SeNPs). The ecologically sound production of selenium nanoparticles using extracts of Withania somnifera extract offers a sustainable and eco-friendly alternative to nanoparticle manufacturing. The synthesized WS-SeNPs exhibit diverse biomedical applications, including antioxidant, antimicrobial, and anticancer activities. The synthesis process involves the reduction of selenium ions from an aqueous solution using Withania somnifera extract as a reducing and stabilizing agent. The green synthesis method offers several advantages over conventional chemical synthesis, including reduced environmental impact, cost-effectiveness, and biocompatibility. The synthesized Withania somnifera selenium nanoparticles (WS-SeNPs) are characterized using various analytical techniques such as Dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), UV-Visble spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD), These characterization techniques provide insights into the size, morphology, crystalline structure &stability. The ecologically sound production of selenium nanoparticles using extracts of Withania somnifera offers a sustainable and eco-friendly approach to nanoparticle fabrication. The synthesized WS-SeNPs exhibit diverse biomedical applications, including antibacterial, and anti-enzymatic activities.