The pivotal aim of the present context was to determine the effect of probiotic (superzist) and medicinal plants (R. coriaria, H. persicum, and M. piperita) powder on growth performance, carcass characteristics, blood parameters, immunity response, and microflora counts of broilers over a 42-day feeding period. One hundred and fifty one-day-old chickens were randomly allocated to the following five treatments: (1) Control diets; (2) control diets?+?0.03% w/v superzist; (3) control diets?+?0.5% w/v R. coriaria; (4) control diets?+?0.5% w/v H. persicum; and (5) control diets?+?0.5% w/v M. piperita. No significant differences among treatments on broiler performance during 29th to 35th days of age, whereas a gradual reduction (P?<?0.05) in the feed efficiency and economic index values between 36th to 42nd days of age, across the treatments versus control diet. Supplementations were increased (P?<?0.05), the colon weight, colon length, and right cecum weight versus control. However, the superzist and phytogenic supplementation slightly increased the jejunum length, ileum length, and left cecum length. The supplementation showed reduced heterophils, increased lymphocytes and monocytes percentage, and decreased heterophils/lymphocytes ratio. Additions of superzist and medicinal plants reduced (P?<?0.05) the total counts of E. coli and improved (P?<?0.05) the cecal lactobacilli. In conclusion, under the appropriate conditions of this investigation, the superzist and tested medicinal plants could undoubtedly be ideal alternatives to the use of existing antibiotics as growth promoters in poultry industry.