Abstract: Background and Objective: Avian Infectious Bronchitis Virus (AIBV) is a highly infectious pathogen of chicken. There is no medication and vaccine developed yet due to its highly mutable nature. The objective was to formulate a blend that can be effective against the viral infection in chicken. Materials and Methods: Several natural essential oils, like, Gardenia jasminoides, Commiphora myrrha, Boswellia serrata, Foeniculum vulgare and Daucus carota with anti-viral properties were blended and tested against Avian Infectious Bronchitis Virus H120 (AIBV H120) strain using in vitro medium. The trial was conducted in an allantoic fluid medium. Different concentration of NOB was inoculated into the allantoic-fluid to challenge with the lethal dose of virus. Results: The Natural Oil Blend (NOB), at its minimum concentration up to 0.01 mL of 0.1%, was effective against the AIBV H120 strain. The NBO concentration lower than 0.1% was not sufficient to deactivate the AIBV H120 strain. The embryos up to 0.1% of NBO treated groups and negative control embryos were alive and tested negative to AIBV H120 strain, whereas the embryos in positive control died and tested positive. Conclusion: The in vitro trial proven that the essential oil Blend can deactivate the Avian Infectious Bronchitis Virus H120 (AIBV H120) in in vitro medium.