Herein, we report for the first time a triadic design of a photoanode consisting of porous TiO2 as an electron collector, CNx as a sensitizer for visible light, and CoPOM as a molecular water oxidation catalyst. The triad photoanode enables visible (λ > 420 nm) light-driven oxidation of water to dioxygen at moderate bias potentials (> 0.2 V vs. RHE). Notably, we show that effective immobilization of CoPOM into the porous structure of the photoanode plays a crucial role in photoanode performance and can be significantly improved using polyethyleneimine (PEI), a cationic polymer that can act as a non-sacrificial, electrostatic linker between the surface of CNx and the CoPOM that are both charged negatively (Scheme 1). The thus achieved optimized immobilization of CoPOM is demonstrated to result in a more efficient transfer of photogenerated holes to water molecules and enhanced oxygen evolution.