In this contribution, a facile one-pot strategy is developed for the assembly of noble metal (Au and Pt) nanoparticles onto one-dimensional ZnO microrods using a green non-toxic reagent amino acid, lysine with two amino functional groups as the capping agent. Noble metal nanoparticles with a small size capped by lysine are formed and simultaneously anchored onto the surface of ZnO. No pre-functionalization of the ZnO support is needed, hence simplifying the synthesis and reducing the fabrication cost. Inspired by the catalytic properties of Au nanoparticles in both catalyst and sensor materials, we have examined the gas sensing performances towards ethanol detection. Obtained results demonstrate that after decoration by Au nanoparticles, the sensor shows significantly enhanced sensing performances in terms of high sensitivity, fast response and recovery, excellent reproducibility and good selectivity. The improved sensor properties are probably ascribed to the catalytic Au promoters and the Schottky barriers at the metal and semiconductor interface.