Methodology to self-assemble metal nanoparticles into three-dimensional mesoscale patterns is a fundamental technique to construct functional materials. Here, we demonstrate that hybridizing an immiscible polymer pair with a metal nanopartide allows the hybrid to self-assemble in the film, resulting in spontaneous alignment of the nanoparticles at the phase-separated interface formed by the constituent polymers. Organic inorganic hybrids composed of polyisoprene, polystyrene, and gold nanoparticle were prepared by multistep "grafting-to" method coupled with alkyne-azide click reaction. The polymer composition can be controlled by the feed ratio of gold nanoparticle to azide ligands. The gold nanoparticle hybrid with symmetric polymer composition forms an "alternating lamellar" structure of polyisoprene and polystyrene, where the gold nanoparticles were forced into the phase-separated interfaces.