Reactive oxygen species (ROS)-mediated mitochondrial dysfunction is one of the major pathological mechanisms of Parkinson's disease. Using inorganic nanomaterials to scavenge ROS has drawn significant interest and can prevent ROS-mediated neurological disorders. We prepared uniform CuxO nanoparticle clusters (NCs) with an average size of 65 +/- 7 nm, using phenylalanine (Phe) as the structure-directing agent. These CuxO NCs functionally mimicked the activities of peroxidase, superoxide dismutase, catalase, and glutathione peroxidase. Because they eliminated ROS, the CuxO NCs inhibited neurotoxicity in a cellular model of Parkinson's disease and rescued the memory loss of mice with Parkinson's disease. The biocompatibility and multiple enzyme-mimicking activities of CuxO NCs offer new opportunities for the application of NCs in biomedicine, biosensing, and biocatalysis.