In this research, we study the effect of adding the Ocimum basilicum leaves powder (OBLP), as broilers chicken feed additive and study its effects on the innate and adaptive immune responses as well as the antioxidant effects in broilers vaccinated with Newcastle disease virus (NDV) vaccine. A total of 100 one-day old broiler were randomly divided into 4 equal groups, the first group (G1) was served as normal control group, the second group (G2) was served as vaccination control group. Groups 3 (G3) and 4 (G4) fed 0.5% and 1% OBLP in diets, respectively, and vaccinated against NDV. The obtained results showed that the adding of OBLP to diets improved the broilers innate immune response which resulted in significant increases in peripheral blood monocyte cells phagocytic activity, lysozyme levels and lymphoid organs / body weight ratios. Adaptive immune response has also been improved as the hemagglutination inhibition (HI) antibody titers against NDV vaccine in G3 and G4 reached the peak earlier, declined slowly and gave significantly higher titer in G4 than other groups at the end of the experiment. The antioxidant effects of OBLP were evident particularly by using high concentration of OBLP as the serum catalase enzyme (CAT) levels were significantly increased whereas malondialdehyde (MDA) were significantly reduced. It could be concluded that the use of OBLP as a feed additive can boost the innate and adaptive immune response to NDV vaccination and improve the antioxidant activity of broilers in a dose dependent manner.