One-dimensional noble-metal nanoparticles (NPs) and their surface modifications to enhance defect states are critical for heterogeneous catalysis. Herein, we report a remarkable enhancement in the catalytic activity of Au-Ag nanoworms (NWs) with Ag coating and its subsequent etching using galvanic replacement reaction (GRR). The Au-Ag NWs were fabricated through an uncomplicated single-step recipe and were subsequently coated with Ag using the seed-mediated approach to form core–shell NWs. The surface roughness of core–shell NWs was further increased by exploiting GRR. The catalytic activity of the nanostructures was studied by the catalytic reduction of the 4-nitrophenol to 4-aminophenol model reaction. The catalytic activity of core–shell and rough NWs is found to be 0.273 min−1 and 0.843 min−1, respectively, which is ∼ 22 and ∼ 67 times higher, respectively, compared to Au-Ag NWs. This makes these nanostructures excellent for catalytic applications.