A triad photoanode comprising a molecular cobalt polyoxometalate (CoPOM) embedded in the porous structure of hybrid photoanodes consisting of polymeric carbon nitride deposited onto an electron collecting porous TiO2 layer is reported for the first time. The photoanodes exhibit complete water oxidation to dioxygen under visible (λ > 420 nm) light irradiation, with photocurrents down to relatively low bias potentials of 0.2 V vs. RHE. Importantly, it is demonstrated that polyethyleneimine (PEI), a positively charged cationic polymer that has been previously reported to enable improved deposition of CoPOM onto various metal oxides, can also act as a highly effective electrostatic linker for immobilization of the anionic CoPOM onto the negatively charged surface of carbon nitride.