The present work evaluated the mesoporous silica nanoparticles (MSNs) as a promising adjuvant in preparation of inactivated avian influenza H9N2 vaccine in chicken. Two inactivated vaccine formulae were prepared by using Montanide™ ISA 71 VG and MSNsas adjuvants. Both vaccine formulae were found to be sterile and safe from local or systemic post-vaccinal reactions. Regarding the vaccine potency, it was found that antibody titer against H9N2 strain was detected in chickens of the group (2) that received the inactivated H9N2 vaccine with MSNs adjuvant and the highest antibody titer (9.6 log₂) was detected early at both 2^nd  and 3^rd-week post-vaccination using haemagglutination inhibition test. On the other hand, the antibody titer against the H9N2 virus in chickens of group (1) vaccinated with the inactivated H9N2 vaccine adjuvanted with Montanide ISA 71 was (5.3 log₂ and 8.6 log₂) at 2^nd and 3^rd-week post-vaccination respectively and reached its maximum value at 4^th-week post-vaccination (9.0 log₂). The results of viral shedding in group (1) vaccinated by Montanide ISA 71 H9N2 vaccine showed only virus shedding of 9.3 × 10² EID₅₀ and Ct value of 35.53 2^nd day post-challenge (DPC) using Real-time RT-PCR. While in group (2) received MSNs and H9N2 vaccine detected no virus shedding at 2^nd DPC, later viral shedding was detected at a rate of 2.4×10² (Ct value of 24,24) and 4.2×10² (Ct value of 26.77) at 4^th and 6^th DPC respectively in comparison with the control unvaccinated group (3) that had the highest virus shedding value ranged from 3.5×10⁷ (Ct value of 20.34) at 2^nd DPC to 3.08×10⁶ (Ct value of 23.92) at 6^th DPC. The present work proved the efficacy of silica nanoparticles as a possible adjuvant for inactivated Avian Influenza H9N2 vaccine.