A new and simple one-pot method for preparing star-shaped ZnO particles was reported. ZnO particles were decorated with Ag nanoparticles (SNPs) by a photodeposition method. The presence of SNC− ions on ZnO surface prevented uncontrollable growth of SNPs. ZnO/Ag particles showed plasmon-enhanced photocatalytic activity toward an AZO dye. SNP improved 16 times the antibacterial activity of ZnO toward 4 bacterial strains.