Establishing artificial photosynthesis systems in a simple but effective manner to mitigate the greenhouse effect and address the energy crisis remains challenging. The combination of photocatalysis technology with bioengineering is an emerging field with great potential to construct such artificial photosynthesis systems, but so far, it has barely been explored in this area. Herein, an artificial photocatalysis platform is constructed with high CO2 conversion and H2O splitting capability by integration of CdS QDs into the intra-subunit interface of H-type ferritin (Marsupenaeus japonicus), a natural ferroxidase through protein interface redesign. The crystal structure of the synthesized CdS QDs with engineered ferritin molecules as bio-templates confirmed the design at an atomic level. Notably, upon absorbing desirable visible light (≈420nm), such a single CdS-ferritin hybrid molecule is able to selectively catalyze the reduction of CO2 into HCOOH (≈90%), meanwhile catalyzing the oxidation of H2O into O2 in an aqueous environment. The O2 production rate reached to 180µmolg-1h-1, and the HCOOH output hit almost 800µmolg-1h-1. This work advances the utilization of the four-helix bundle structure for crafting artificial photosynthesis systems, facilitating the seamless integration of bioengineering and photocatalysis technology.