A bimetallic metal–organic frameworks (MOFs)-templated strategy was developed to fabricate mesoporous CdxZn1−xS polyhedrons with improved photocatalytic hydrogen evolution activity, and the formation mechanism of these mesoporous polyhedrons was discussed in detail. Incorporating Cd atoms, the Brunauer–Emmett–Teller surface areas of mesoporous CdxZn1−xS polyhedrons were significantly increased (271 m2/g), providing more exposed active sites compared with ZnS. In addition, suitable conduction band potential (< −0.55 eV) of the mesoporous CdxZn1−xS polyhedrons was also beneficial for the photocatalysis. Impressively, by the co-effects of mesoporous structure and modified conduction band, the mesoporous CdxZn1−xS polyhedrons exhibited better photocatalytic activity for hydrogen evolution than most reported photocatalysts without noble metals. The maximum hydrogen evolution rate of the CSZ3 reached 4.10 mmol/(h g) under visible-light irradiation and without any cocatalyst condition. This facile strategy for the construction of mesoporous CdxZn1−xS polyhedrons provided a deep insight to fabricate other metal sulfides for a variety of photochemical applications.