This study aimed to evaluate the effect of curcumin supplementation on growth performance, carcass parameters, behavior characteristics, blood metabolites, antioxidant status, and tissue histomorphology in heat-stressed broiler chickens. 120 one-day-old chicks were reared over 35 days in two separate rooms; one designated to induce heat stress and the other to maintain a normal temperature. After a completely randomized design, birds were divided into four treatments, each with 6 replicates of 5 chicks. Treatments were thermoneutral control group fed basal diet, heat-stressed group fed basal diet, curcumin-supplemented group fed basal diet with 1g/kg curcumin, and curcumin-supplemented heat-stressed group fed basal diet with 1g/kg curcumin. Broilers supplemented with curcumin and reared under heat stress conditions grew significantly (P < 0.05) more than other groups with improved carcass parameters. The proportion of birds exhibiting standard behavior was enhanced (P < 0.05), while the duration of Tonic immobility test was significantly decreased (P < 0.05) in curcumin-supplemented groups. Total protein, albumin, globulin, HDL, growth hormone, T3, T4, TAC, CAT, SOD, IL -10, C3, and Lysosomes were significantly increased (P < 0.05). At the same time, cholesterol, LDL, triglycerides and MDA, IL-1β, and IFN-γ levels were significantly reduced (P < 0.05) by adding curcumin. Curcumin effectively reversed the heat stress-induced histopathological changes in the liver, spleen, bursa, intestine, and breast muscles. These results indicate that curcumin can mitigate the negative effects of heat stress on health and stimulate immunity and antioxidant status in broiler chickens