The hollow core–shell Co9S8 @ZnIn2S4/CdS nanoreactors are fabricated by growing ZnIn2S4 nanosheets and CdS quantum dots on hollow Co9S8 nanocages for photocatalytic CO2 reduction and H2 generation. Because of unique structural and compositional advantages, Co9S8 @ZnIn2S4/CdS exhibits a significant photocatalytic BPA degradation of 90.62%, CO production of 82.10 μmol g−1 h−1, and H2 evolution rate up to 1419.14 μmol g−1 h−1. Excellent photocatalytic performances are attributed to unique core-shell architecture, which can improve the scattering and refraction efficiency of incident light, and the separation and migration of photoinduced carriers. Furthermore, Co9S8 @ZnIn2S4/CdS possesses a broad absorption spectrum facilitating outstanding photothermal performance. The photocatalytic mechanism for the nanoreactor has been discussed in detail.