Selenium (Se) is an essential trace element with diverse physiologi- cal functions related to cellular homoeostasis, body metabolism and antioxidant defence. Se is an integral constituent of at least 25 selenoproteins in the body that regulate cellular redox and antioxidant defence enzymes systems control free radicles of reac- tive oxygen species . Dietary Se plays key role in immunity, growth and fertility in chickens, which require optimum levels in their diets to maintain high reproductive and productive performance of birds. In the last decade, dietary supplementation with selenium nanoparticles (SeNPs) has enhanced the growth performance, feed conversion ratio, reproductive performance, egg production, immune response and antioxidant status, as well as improved the quality of meat and eggs and promoted microflora. Se has been shown to increase relative weights of immune-related organs (burse and thymus) to enhance immunity. Feeding Se-NPs can improve antioxidant status and glutathione peroxidase activities in both broilers and layers. Use of Se-NPs at 0.9 mg/kg diet in broilers improved the intestinal health via increasing the popula- tion of beneficial bacteria and producing short-chain fatty acids. This review focuses on the significance of SeNPs in poultry industry and provides insights about its comparative advantages over con- ventional sources of Se in poultry diets.