Assembly of nanoparticles in an ordered fashion can create advanced superstructures. The controlled dimensions of these nanostructures into 1D and 2D morphologies allow them to be applied in the field of optics, magnetism, and electronics. The chapter will discuss different unique approaches to bring the inorganic nanoparticles (metallic, semiconductor, and magnetic) together and understand the mechanisms in detail for creating such well-defined morphologies. The methods include noncovalent interactions between nanoparticle–nanoparticle, nanoparticle–polymer, nanoparticle–biomolecules, and so on to generate nanorods, nanowires, nanoplates, and nanosheets. Once the nanostructures are formed the physical responses of the material are modulated compared to the individual nanoparticles. The tuning of the optical, magnetic, and electronic behavior due to their geometrical change in the assembled structures holds a great promise to design new materials with specific applications in the field of biology and material science. The physical properties of nanoparticles combined with the functional attributes of polyelectrolytes and biomolecules also provide a new route for the creation of hybrid materials. The key challenge for the assembly of nanoparticles is not only to create complex structures, but also to create 1D or 2D structures for designing circuits, sensors, and drug-delivery agents.