Nanotechnology, an emerging and promising technology, has been implicated to revolutionize the poultry industry. The main aspect of nanotechnology was to modify or alter the particle size into nanometers and thereby alter the physical as well as chemical features of the particular molecules. Selenium (Se), an essential trace element, can play an immense role in the maintenance of diverse physiological functions, body metabolism and cellular homeostasis, and the performance of poultry. Selenium nanoparticles (Se-NPs) are of growing importance due to its nutrients digestibility, medicinal therapy, targeted drug delivery system, and production of vaccines. Se-nanoparticles are having importance due to its high bioavailability and digestive efficiency. Se-NPs have been implicated to increase relative weights of immune-related organs (burse and thymus) to enhance immunity and thereby modulate egg production as well as the reproductive performance of birds. The present review is highlighted on the significant role of nano-selenium on reproductive performance and immunocompetence in poultry as comparative advantages over conventional sources of Se in poultry diets.