Three-dimensional (3D) Ag/ZnO assemblies with porous nanosheets as building blocks have been designed and selectively prepared via a facial solution method followed by topological morphology conversion with low temperature calcination. The samples were characterized thoroughly by using XRD, SEM, TEM, HRTEM, N-2 isotherms, UV-vis spectroscopy, PL, EIS, Mott-Schottky plots, and photocurrent response. The as-prepared 3D Ag/ZnO architectures were evaluated as photocatalysts for hydrogen evolution and organic pollutants removal from aqueous solution, which demonstrates superior sun-light driven photocatalytic activities to those of ZnO architectures. Nearly 100% photocatalytic degradation of 10 ppm 4-nitrophenol was obtained just for 25 min and 0.4436 mmol g(-1) h(-1) of hydrogen production rate was achieved over Ag/ZnO architectures. The photo current of the Ag/ZnO photoelectrode showed an enhancement of three times of ZnO architectures. The enhanced photocatalytic activity may be attributed to the synergetic effect between 2D ZnO porous single crystalline nanosheets and sliver components, which could not only accelerate separation and migration efficiency of charge carries, but also enhance charge-collection efficiency.