This study aimed to evaluate the supplementation of dried defatted black soldier fly larvae (BSFL; Hermetia illucens) in the diets of growing buffalo calves. BSFL was prepared to be added in the form of dried powder. Fifteen buffalo calves, 5 months of age and 122.44±12.26 kg of body weight, were divided into three experimental groups in a randomized block design, receiving three experimental diets as follows: diet 1 (D1) represented the basal diet with no supplementation, while diet 2 (D2) and diet 3 (D3) represented the same basal diet supplemented with 5 and 10 kg/ton of BSL, respectively. A growth trial was performed to calculate average daily gain (ADG) for 15-day intervals during 90 days. A digestibility trial was conducted to investigate nutrient digestibility using the acid insoluble ash (AIA) method. Dry matter intake (DMI) and dry matter conversion (kg DM/kg gain) were also observed. Results showed that BSFL supplementation at 10 kg/ton significantly (p ≤ 0.05) improved all nutrients digestibility, ADG, DM conversion, plasma total protein, and albumin. Supplementation of BSFL at 5 kg/ton significantly increased ADG with significant improvement in the digestibility of ether extract (EE) and nitrogen-free extract (NFE) compared to control group. Supplementation did not significantly affect DMI. All blood plasma biochemical parameters were within the average values of blood characteristics of buffalo calves without any deleterious effect on liver or kidney functions as affected by both levels of BSFL supplementation. BSFL supplementation significantly (p ≤ 0.05) increased plasma triglycerides in a linear pattern, and conversely, it appeared to have the ability to lower plasma cholesterol concentration.