To provide a safe growth promoter, the present study has investigated the effects of different levels of cold-pressed clove oil (CCPO) on growth performance, carcass traits, blood biochemistry, and intestinal microbial population of growing Japanese quails. A total of 300 quails (1-wk old) were randomly divided into 3 treatment groups: control basal diet, basal diet +0.75 mL oil/kg diet, and basal diet +1.5 mL oil/kg diet. Quails fed with 1.5 mL clove oil/kg diet showed a 3.43% improvement in live body weight vs. control group. Similar trend was observed for daily body weight gain. Feed intake gradually increased (P < 0.01) with an increase in clove oil level. The best feed conversion rate was reported for the control group, followed by the group treated with 1.5 mL CCPO/kg diet during the whole period (1 to 6 wk of age). Total globulin differed significantly in 1.5 mL CCPO/kg diet group. Antioxidant enzyme activities, lipid profile, and reduced glutathione concentrations significantly improved in a dose-dependent manner. Blood urea nitrogen, creatinine, malondialdehyde, 8-hydroxy-2΄-deoxyguanosine, and protein carbonyl levels significantly decreased in quails supplemented with 1.5 mL CCPO/kg diet vs. control group. Serum levels of insulin-like growth factor-1, insulin, growth hormone, and thyroxine significantly increased in quails supplemented with 1.5 mL CCPO/kg diet vs. control group. The intestinal bacterial population, coliforms, Escherichia coli, and Salmonella spp. in the ileal content were lower (P < 0.05) in groups treated with oil (1.5 mL/kg) vs. control group. Thus, dietary supplementation with antimicrobial CCPO (1.5 mL/kg diet) could enhance growth performance, improve health status, and reduce intestinal pathogens in Japanese quails.