CuGaS2 is one of the most excellent visible-light-active photocatalysts for CO2 reduction and water splitting. However, CuGaS2 suffers from serious deactivation in photocatalytic reactions, which is mainly due to the photo-oxidation induced self-corrosion (Cu+ to Cu2+). Here, we constructed a CuGaS2/CdS hybrid photocatalyst dominated by a Z-scheme charge transfer mechanism. The transfer of photo-generated electrons from excited nanocrystalline CdS to CuGaS2 across the coherent interface reduces Cu2+ formation and favors Cu+ regeneration. This process suppresses the deactivation of CuGaS2 and maintains high performance. Both the activity and stability of photocatalytic CO2 reduction to produce CO over the CuGaS2/CdS hybrid were remarkably improved, which was approximately 4-fold higher than CuGaS2 and 3-fold higher than CdS in converting CO2 into CO. Our study demonstrates that even using the semiconductors prone to photo-corrosion, it is possible to obtain satisfactory catalytic activity and stability by designing efficient Z-scheme-charge-transfer-type photocatalysts.