Selenium nanoparticles have been widely used in the various areas especially in medical field for its anticancer and immune modulatory properties. To reduce the toxic chemicals released by chemical process, the present work was aimed at synthesis of selenium nanoparticles by microbes. In this study, microbes were isolated from soil samples from different areas of Bangalore and screened for the antioxidant activity by DPPH assay. The organism with highest antioxidant activity (IC50 value = 11.6µg/mL) was identified as Bacillus species. Under experimental conditions, this microbe along with sodium selenite synthesised selenium nanoparticle indicated by the colour change of the medium to reddish orange. The synthesised selenium nanoparticles were further characterised. From UV-Vis spectrophotometry, the maximum peak was obtained at 266.5nm. The FT-IR analysis showed peaks at different wavelengths with the maximum of 3200cm-1 showing the presence of alcoholic group. The shape and size of the selenium nanoparticles was also calibrated by SEM analysis as oval and 209nm-748nm respectively. The nanoparticles were further analysed for antimicrobial assays by well diffusion method against E. coli, S. aureus, P. aeruginosa, St. mutans and antifungal assay against the strains of C. albicans, A. niger and A. flavus. The highest zone of inhibition was observed against E.coli (1.7 cm) at a concentration of 400µg and maximum for C. albicans (2.5cm) at a concentration of 400µg. Microbial synthesized nanoparticles emerges as a promising medicine in curing different disorders because of its potent antioxidant and antimicrobial activity.