Abstract The precise molecular design of functional dendritic polymers enables the accumulation of multiple metals within a molecular cage. We have established a synthesizing methodology of metallodendrimers where the number of constituent atoms, the choice of elements, and the composition ratio were precisely controlled through an intramolecular Lewis acid-base interaction at each branch of phenylazomethine dendrons. Due to their inherent capsule effect, chemical reduction of metallodendrimers generates homogeneous subnanoparticles with a particle size of about 1 nm in diameter within the dendrimer cage. Fabricated subnanoparticles show amorphous crystal structures with distorted and fluctuated surface atoms and, with such a unique atomic structure, induce peculiar electronic states, surpassing unique and discrete physical and chemical properties of conventional nanoparticles and bulk metals. In this paper, we review the dendrimer-derived synthesis of atomic hybrid subnanoparticles and its research application established in our laboratory.