Supported Ni and Ir nanocatalysts have been used in CO2 dry reforming of methane (DRM); however, their fast deactivation limited further applications. In this research, we introduced NiO nanoparticles (NPs) on the SiO2 surface ahead of the addition of the Ir source for the bimetallic Ir-Ni/SiO2 catalyst. The homogeneous NiO NPs provide finite spaces to prohibit the agglomeration of Ir NPs under H-2 reduction. The Ir-Ni/SiO2 catalyst was obtained with ultrasmall bimetallic NPs (1.4 nm) uniformly distributed on the SiO2 surface. Owing to the synergistic effects within the bimetal, the catalytic performance on the fabricated bimetallic catalyst into the DRM reaction is significantly enhanced, with 1.2 times higher than the sum of the Ir and Ni monometallic catalysts. Besides, the side reaction of the reverse water-gas shift reaction is effectively suppressed, and the stability is also improved. This facile strategy provides another approach to fabricate ultrasmall and homogeneous bimetallic catalysts for efficient storage and conversion of fossil fuels.