A recently emerging visible light-absorbing semiconductor, brown TiO2 (b-TiO2), was coupled with a CoFe Prussian blue (PB) analogue to prepare an entirely earth-abundant semiconductor/water oxidation catalyst hybrid assembly. PB/b-TiO2 exhibits a sevenfold higher photocatalytic water oxidation activity compared to b-TiO2. An elegant band alignment unified with the optical absorption of b-TiO2 and excellent electronic dynamics of PB yield a high-performance photocatalytic system.