The splitting of water into H2 and O2 using solar energy is one of the key steps in artificial photosynthesis for the future production of renewable energy. Here, we show the first use of CoP and Pt nanoparticles as dual co‐catalysts to modify graphitic carbon nitride (g‐C3N4) polymer to achieve overall water splitting under visible light irradiation. Our findings demonstrate that loading dual co‐catalysts on delaminated g‐C3N4 imparts surface redox sites on the g‐C3N4 nanosheets that can not only promote catalytic kinetics but also promote charge separation and migration in the soft interface, thus improving the photocatalytic efficiency for overall water splitting. This robust, abundant, and stable photocatalyst based on covalent organic frameworks is demonstrated to hold great promise by forming heterojunctions with CoP and Pt for catalyzing the direct splitting of water into stoichiometric H2 and O2 using energy from photons. Two are better than one: Graphitic carbon nitride (g‐C3N4)‐modified co‐catalysts with two different functions are prepared to achieve overall water splitting under visible light irradiation in the absence of any sacrificial agent. CoP colloidal nanocrystals and Pt nanoparticles act as co‐catalysts that not only effectively suppress the recombination of carriers but also greatly enhance reaction kinetics. However, it is important to achieve pure water splitting that a suitable loading of the co‐catalysts is chosen.