The objective of the study was to examine the effect of varying levels of oleuropein supplementation on productive performance and physiological parameters of Bandarah cockerels. A total of one hundred (28-day-old) Bandarah cockerels were weighed individually and randomly assigned to four treatment groups. From 4 to 16 weeks of age, five replicates (5 cockerels per rep.) were used to represent each treatment group. A basal diet group 1without any supplements (control), while groups 2, 3, and 4 received diets supplemented with 50, 100, and 150 mg of oleuropein/kg feed, respectively. Body weight and body weight gain were increased (p < 0.001) when used 100 and 150 mg oleuropein/kg feed compared to the other treatments. Feed consumption was not impacted, but feed conversion ratio enhanced overall period when oleuropein was added. Carcass characteristics had not affected by oleuropein addition while, bacterial count in the intestine were reduced by increasing oleuropein levels. The inclusion of oleuropein in the diet of cockerels reduced (p < 0.001) level of LDL and total cholesterol, activity of AST,ALT, and ALP enzymes, while, increased HDL level compared to the control diet. Adding oleuropein at varying concentrations Heterophils and the H/L ratio dropped, whereas WBC and lymphocytes increased. The immunoglobulin (IgG and IgM) levels improved in reaction to oleuropein treatments; the group fed with 150 mg/kg diet had the highest levels. Total plasma antioxidant capacity (TAC) and superoxide dismutase (SOD) activities were increased by increasing oleuropein levels, while malondialdehyde (MDA) was significantly decreased compared with control group. Oleuropein supplementation at all levels showed improved economic efficiency compared with control group. The relative economic efficiency of a diet containing 100 mg oleuropein/kg feed increased by approximately 28.4% than the control group. In conclusion, oleuropein supplementation at a dosage of up to 150 mg/kg feed enhanced growth performance, intestinal microbial count, physiological parameters and anti-oxidative status of Bandarah cockerels during the growth period and the best value was 100 mg/kg.