The ashwagandha (Withania somnifera) root powder (ARP) was assessed as a dietary supplement to enhance growth in the Nile tilapia (Oreochromis niloticus) fingerlings. The study involved incorporating ARP at levels of 0, 1.5, 3, and 4.5% into the diets, corresponding to 0, 15, 30, and 45g/ kg in diets D1, D2, D3, and D4, respectively. A total of 180 fish, each with an initial body weight of 10.36± 0.821g, were distributed across 12 aquariums, with 15 fish per aquarium. The results indicated that ARP contains 4.21% CP, 34.90% CF, 0.32% EE, with gross energy of 4032kcal/ kg DM, and metabolizable energy of 216.33kcal/ kg DM. All diets tested were isocaloric and isonitrogenous. Fish fed with ARP demonstrated improvements in final weight (FW), total body weight gain (TBWG), average daily gain (ADG), and specific growth rate (SGR), while survival rates (SR) were 100%, and mortality was zero across all groups. Feed conversion ratio (FCR) significantly improved with higher ARP inclusion. Additionally, ARP inclusion led to reduced levels of AST, ALT, cholesterol, and LDL in the blood. Fish body composition, including moisture, organic matter (OM), crude protein (CP), ether extract (EE), and gross energy content, showed significant enhancement, whereas dry matter (DM) and ash content decreased. Energy retention and protein productive value (PPV) also significantly increased. The findings suggest that ARP can be an effective growth promoter in the diets of the Nile tilapia without adverse effects on growth performance or blood parameters.