Metal-graphene nano-composites with low volume/weight fractions of graphene inclusions exhibit significantly high mechanical strength and hardness. However, manufacturing of metal-graphene nano-composites for high strength, hardness, and elastic properties is in its infancy stage. Enhancing mechanical strength of materials has been of great interest worldwide by introducing secondary phase reinforcement particles into the metal structure. Researchers across the world have applied this method to improve the mechanical properties of the composite, such as elastic modulus, tensile strength, compression strength, bending strength, toughness, and hardness. A highly desirable output was achieved by the above research effort, although the development of cost-ffective manufacturing techniques of metal composites is still an unsolved problem. In this study, we focus on searching new reinforcing materials as “nano-fillers” in composites of vital importance. To improve the role of nano-fillers as new reinforcing particles, some of the key features must be considered during the manufacturing process to further improve the mechanical strength of the material. These include surface and high aspect ratio, strong binding property with metal matrix after inclusion, and homogeneous dispersion of reinforcing particles in the matrix to further avoid agglomeration. The whole process should also be cost effective. With the above approach, many types of reinforcing nano-inclusions, such as ceramic nanoparticles, nano-fibers, metallic nanoparticles and carbon nanotubes have been highly exploited in effective materials engineering. This application of nanotechnology in manufacturing of improved metal composites with high mechanical properties is the subject of interest of this paper, which mainly needs intense research focus and has scope for further advancements in materials engineering. With the approach, ceramic nanoparticles, nanofibers, metallic nanoparticles and carbon nanotubes have been effectively exploited as reinforcing nanoscale inclusions. It was concluded that the strengthening effect of graphene reinforcement in the metal-graphene composites is much more significant than the combined effects of the nano-layered structure. Thus, the latest and very effective method to manufacture metallic materials with high strength, hardness, and Young’s modulus is to implant graphene platelets and sheets of a few layers in metallic matrices.