The construction of a nano-heterojunction photoanode is an attractive strategy for accelerated charge separation. Here, α-Fe₂O₃ nanorod arrays (Fe₂O₃ NAs) top-decorated with an MIL-101 layer are achieved via the CVD method for constructing one intimate contact between two layers. The systematical analysis in time-dependent deposition shows that the photoelectric response capability can be modulated by controlling the thickness of the MIL-101 layer as a function of CVD duration. An optimized thickness of 4–6 nm MIL-101 in the Fe₂O₃/MIL-101 photoanode presents the best PEC performance with the IPCE of 25% and a photocurrent density of 1 mA cm⁻² at 1.3 V vs. RHE, about 2.5 times higher than that of pristine Fe₂O₃ NAs. The exciton lifetime and the electrochemical active surface area of the composited electrode are greatly improved by 14 and 1.3 times respectively compared to that of pristine Fe₂O₃. The notable advancement can be attributed to the fact that the top-decorated MOF layer can promote charge separation efficiency led by the built-in electric field and form a tight interface between Fe₂O₃ and MIL-101 with a favorable diffusion length for holes, as well as the fact that it can reduce surface defects and provide more reaction sites.