The current study was done to evaluate the impact of supplementing buffalo calves with Spirulina platensis (SP) on the nutrients digestibility, dry matter intake (DMI), average daily gain (ADG), dry matter (DM) conversion, and some biochemical blood plasma parameters. SP was cultivated, sun-dried, and ground to a fine green powder. Fifteen buffalo calves were equally divided into three groups, where three experimental diets were offered: a control diet without SP supplementation (SP0) and diet supplemented with 5 and 10 kg SP powder/ton for SP5 and SP10, respectively. Results demonstrated that, compared to the control diet, SP5 had a significant (P ≤ 0.05) increase in organic matter (OM), ether extract (EE), and nitrogen-free extract (NFE) digestibility, whereas SP10 had a significant (P ≤ 0.05) increase in all nutrients digestibility. Non-significant effect of supplementation on DMI was recorded. ADG was increased linearly (P ≤ 0.05) with the level of supplementation. Both levels of supplementation significantly (P ≤ 0.05) increased DM conversion, blood plasma total protein, albumin, and triglycerides, and conversely decreased (P ≤ 0.05) blood plasma cholesterol. No evidence of undesirable effect on either liver or kidney function was found due to supplementation.