Poor wettability and weak graphene/Cu interface limit the mechanical properties' enhancement in graphene/Cu composites. This study devised an interface enhancement approach by Ag decoration of graphene nanoplatelets (Ag-GNPs) and Ag decorated nitrogen doped graphene (Ag-N-GNP) without oxide (during decoration) and carbide (during sintering) formation. Sonication was used to functionalize GNPs for decoration with Ag nanoparticles (NPs) and Cu composites (Ag-GNP/Cu and Ag-N-GNP/Cu) were fabricated using cold pressing (low-pressure) and sintering. 2-Ag-GNP/Cu (2 vol% of Ag-GNPs) and 2Ag-N-GNP/Cu (2 vol% of Ag-N-GNPs) possessed highest sintered density. In addition, 2-Ag-GNP/Cu and 1-Ag-N-GNP/Cu showed highest microhardness and tensile strength (theoretical), respectively. Higher concentration of Ag NPs on GNPs in Ag-N-GNP (oxygen and nitrogen functionalization) showed lower mechanical properties for Ag-N-GNP/Cu compared to Ag-GNP/Cu with limited Ag NPs on GNPs (oxygen functionalization). Interface modification strategy with noble metal NPs bridging between GNP and Cu suggests controlled functionalization and noble metal NPs' attachment on GNPs for effective mechanical properties' enhancement in graphene Cu composites. (c) 2024 The Society of Powder Technology Japan. Published by Elsevier BV and The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.