Photoelectrochemical (PEC) water splitting to produce hydrogen energy has attracted considerable attention for solving current energy and environmental crises. However, the intrinsically high electron–hole recombination and low charge mobility greatly diminish the PEC efficiency. Herein, we demonstrated that metal organic framework MIL-53(Fe) could serve as an efficient hole-transfer co-catalyst to significantly improve the PEC performance of Mo-doped BiVO₄ photoanodes toward water oxidation under solar irradiation, which is much higher than that of the traditional FeOOH co-catalyst under the same conditions. More specifically, owing to the unique 3D interlinked nanochannel and confinement effect of Fe atom sites, the charge separation, hole transport at the interface, and interactions with H₂O molecules have been effectively facilitated, which thus allows for enhancing PEC water oxidation properties.