Enzyme-mimicking inorganic nanoparticles, also known as nanozymes, have emerged as a rapidly expanding family of artificial enzymes that exhibit superior structural robustness and catalytic durability when serving as the surrogates of natural enzymes for widespread applications. However, the performance optimization of inorganic nanozymes has been pursued in a largely empirical fashion due to lack of generic design principles guiding the rational tuning of the nanozyme activities. Here we choose Au surface-roughened nanoparticles as a model plasmonic nanozyme that combines peroxidase-mimicking behaviors with tunable plasmonic characteristics to demonstrate the feasibility of fine-tuning nanozyme activities through plasmonic excitations using visible and near-infrared light sources. Taking full advantage of the unique plasmonic tunability offered by Au surface-roughened nanoparticles, we were able to unravel the detailed relationship between plasmonic excitations and nanozyme activities that underpins the hot electron-mediated working mechanism of peroxidase-mimicking plasmonic nanozymes.