Photocatalytic conversion of chemical fuels has emerged as a most challenging subject in photocatalysis which is considered as one of the sustainable solutions for environmental issues related to the energy shortage and anthropogenic carbon emissions. Herein, unique heterostructures of ZnCdS nanoplates with Bi2S3−terminated edges were prepared through a facile cation exchange pathway, by which the controlled photocatalytic CO2 conversion was achieved. The optimized BZCS–NS−5 photocatalyst exhibited an excellent capacity of CO2 photoreduction with a CO production rate of ca. 513.2 ± 5.1 μmol g−1 h−1 and a selectivity of ca. 91.0%, which were among the highest activities for sulfide photocatalysts documented in the literature. The outstanding photocatalytic performance was attributable to the formation of Z−scheme heterostrucutres between Bi2S3 and ZnCdS, in a way the separation and migration of photocarriers were accelerated. This work thus provides a feasible strategy for the construction of heterostructures to enhance the activity and selectivity of CO2−to−CO conversion via delicate design and controlled synthesis of photocatalysts.