The current study was designed to investigate the effects of dietary Spirulina inclusion at different levels on growth performance, antioxidant status, carcass traits and blood hematology of broilers subjected to cyclic heat stress. A total of 150 one-day-old Ross broiler chicks were randomly divided into three experimental groups with 5 replicates with 10 birds for each. The first group was provided with a basal diet and served as a control. Meanwhile, others were fed a basal diet supplemented with Spirulina at a concentration of 1 or 2 g/kg diet, respectively. The experiment was conducted during hot climate of July with ambient temperature of 30 ± 1 ◦C, Spirulina supplementation to heat-stressed broilers was able to alleviate the negative impacts of heat stress on the final average daily gain, body weight and feed conversion ratio, with the best impacts on the chickens fed Spirulina at level of 2 gm/kg diet. Further, Spirulina supplementation significantly affected blood lipid profile by reducing serum total cholesterol, low-density lipoprotein (LDL) and increasing high-density lipoprotein (HDL) levels. While the thyroid hormones T3 and T4 were increased by Spirulina supplementation. In addition, spirulina supplementation at 1 or 2 g improved carcass dressing percentages. It concluded that dietary Spirulina supplementation at 1 or 2 g/kg diet to broilers reared under heat stress conditions can effectively improve broiler production performance, blood constituents and physiological status