Single-atom catalyst has drawn significant attention in the field of environmental engineering nowadays. In this research, single atoms Pt have highly dispersed on the wurtzite ZnO nanoflowers, evidenced by the high-angle annular dark field (HAADF-STEM) image. The single atom Pt/ZnO catalyst (SAPt/ZnO) was used to degrade organic dye through the piezo-photocatalytic process. The results showed that the SAPt/ZnO catalyst could fully decolorize 10 ppm RhB dye in 60 minutes under synergetic ultrasonication and light irradiation with Kobs of 0.089 min-1, while pristine ZnO nanoflowers have a Kobs of 0.050 min-1, proves the fact that the decoration of single atom Pt increases catalytic activity. In comparison, Kobs of SAPt/ZnO were found to be 0.021 min-1 for ultrasonicate only and 0.014 min-1 for light irradiation only, which indicates the strong enhancement of the piezo-photocatalytic effect. The theoretical study was then conducted with the density functional theory (DFT) approach to investigate the detailed mechanism. The Pt single atom was found to adsorb on the ZnO (101) surface with an adsorption energy of -1.28 eV, and the charge was localized on the top of the Pt atom after the chemisorption of SAPt on ZnO surface, providing abundantly active sites on the surface of the ZnO nanoflower.