In this research, graphene/Al6061 aluminum matrix nanocomposites were fabricated by stir casting, and the influence of graphene nanoplates on microstructure and mechanical properties of the 6061 aluminum alloy were investigated by field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy, tensile and hardness testing analysis methods. The major limitation in the utilization of 6061 aluminum alloy in heavy stress applications such as airplane fuselages, wings, internal panels, and luxury vehicles chassis is low strength and hardness. This deficiency of 6061 aluminum alloy was tackled by successful reinforcement of graphene nanoplates in 2, 4, 6, 8 and 10 wt.%, using the stir casting process. The FESEM micrographs showed that the graphene nanoplates were uniformly distributed in the 6061-aluminum matrix alloy and tensile strength, hardness, and yield strength enhanced remarkably as compared with unreinforced 6061 aluminum alloy. The as-cast tensile strength, hardness, and yield strength of the graphene/Al6061 nanocomposites were improved by 127%, 158%, and 402%, respectively, compared with the unreinforced Al6061 alloy. It is concluded that the nano thickness of graphene, reinforcement quantity, and manufacturing process are the major factors for the enhancement of microstructure and mechanical properties of graphene/Al6061 nanocomposites. © 2022 The Korean Society for Composite Materials and IOP Publishing Limited.