A gas-phase-controlled synthetic approach is demonstrated to fabricate Ag-ZnO hybrid nanostructure as a high-performance catalyst for photodegradation of water pollutants. The degradation of rhodamine B (RhB) was used as representative, which were tested and evaluated with respect to the environmental pH and the presence of dodecyl sulfate corona on the surface of the catalyst. The results show that a raspberry-structure Ag-ZnO hybrid nanoparticle cluster was successfully synthesized via gas-phase evaporation-induced self-assembly. The photodegradation activity increased significantly (20×) by using the Ag-ZnO hybrid nanoparticle cluster as a catalyst. A surge of catalytic turnover frequency of ZnO nanoparticle cluster (>20×) was observed through the hybridization with silver nanoparticles. The dodecyl sulfate corona increased the photocatalytic activity of the Ag-ZnO hybrid nanoparticle cluster, especially at the acidic and neutral pH environments (maximum 6×), and the enhancement in catalytic activity was attributed to the improved colloidal stability of ZnO-based nanoparticle cluster under the interaction with RhB. Our work provides a generic route of facile synthesis of the Ag-ZnO hybrid nanoparticle cluster with a mechanistic understanding of the interface reaction for enhancing photocatalysis toward the degradation of water pollutants.