© 2021 Elsevier B.V.The graphene nanoplatelet (GNP) reinforced nickel matrix composites (Ni-GNP) have been processed using two different ball milling approaches, viz, dry ball milling (DM) and solution ball milling (SBM), followed by consolidation using spark plasma sintering (SPS) technique. The composites were reinforced with varying GNP concentration (0.5–2 wt%) and were milled for up to 12 hr to investigate the effect of premixing technique, milling duration, and GNP concentration on the grain size, microstructure, the dispersion of GNP in the nickel matrix, and mechanical behavior of these composites. Ni-GNP nanocomposites exhibited improved microhardness and tensile strength compared to pure nickel, primarily attributed to grain refinement and load transfer strengthening due to the uniform dispersion of these GNPs within the nickel matrix, promoting effective load transfer during tensile deformation. Ni-0.5GNP composites processed via dry milling followed by SPS exhibited the highest tensile yield strength of 586 MPa as compared to pure nickel and other Ni-GNP composites. The contribution of each strengthening mechanism in the overall improvement in yield strength of Ni-GNP composites has been qualitatively calculated/quantified and compared with experimentally obtained tensile properties.