The interfacial interaction between graphene and Cu restricts the efficacious properties' enhancement due to poor wettability between the reinforcement and matrix. Herein, we reported an interface modification strategy by Au decoration of graphene nanoplatelets (Au-GNPs) without carbide/oxide formation. Sonication was used to induce defects in GNPs, which were then decorated with Au nanoparticles and used to fabricate a composite material with Cu (Au-GNP/Cu) via low pressure cold pressing and sintering. Sonication parameters' optimization depicted higher exfoliation of GNPs with lower defects at lower sonication amplitude and higher sonication duration which resulted in relatively monodispersed Au nanoparticles attached to the GNPs' surface. The Au-GNP/Cu composite with 1 vol showed highest sintered density, hardness and calculated tensile strength which decreased at higher Au-GNP content. The proposed interface design with noble metal nanoparticles acting as bridges between GNP and Cu, opens new horizons for superior mechanical properties of composites. © 2023