Metallic sulfides have emerged as highly active, durable, and robust electrocatalysts for the electrocatalytic hydrogen evolution reaction (HER) due to their intriguing electronic and catalytic properties. One of the important strategies to further enhance their HER performance is to build multimetallic nanostructures by tuning the electronic state. Here we combine multimetallic structures and metal sulfides, and report an efficient strategy for the in situ surface-derivation of molybdenum sulfide nanosheets (MoS2 NSs) on Ag-Pd-Mo alloy nanowires (AgPdMo NWs) to form AgPdMo/MoS2 NWs. The heterostructure incorporates AgPdMo NWs with high conductivity and MoS2 NSs with abundant active sites, which act synergistically in alkaline solution. The as-tuned AgPdMo/MoS2 NWs exhibit Pt-like electrocatalytic performance for the HER, with a small overpotential of 54 mV at a current density of 10 mA cm-2 and a low Tafel slope of 72 mV dec-1. The present work demonstrates a potential strategy for designing heterostructures with multimetallic composition by in situ surface-derivation with enhanced performance in water splitting.