Recently, the ecofriendly techniques for production of nanohybrids using natural biomass have aroused great attention. This study reported a green and facile synthesis of highly dispersed supported metal catalysts using sesbania powder (SP) extracted from the natural sesbania plant. Well-dispersed Ni/SiO2 catalysts were effectively fabricated by an SP-assisted sol-gel method. The influencing factors including the additive amounts of SP, metal loadings, and metal types on the physicochemical properties of supported catalysts were primarily investigated. The testing results revealed that the additive SP significantly facilitated the uniform distribution of metal species during heat treatment, leading to the existence of ultrasmall nanoparticles (<4 nm) and high dispersion of supported metal. The as-prepared Ni/SiO2 catalysts were applied to the dry reforming of methane and demonstrated excellent catalytic performance due to the prevention of the agglomeration of Ni species and fabrication of Ni embedded in the silica framework through the introduction of SP.