Incorporating metal nanodots (NDs) into heterostructures for high charge separation and transfer capacities is one of the most effective strategies for improving their photocatalytic activities. However, controlling the space distribution of metal NDs for optimizing charge transport pathways remains a significant challenge, particularly in two-dimensional (2D) face-to-face heterostructures. Herein, we develop a simple targeted self-reduction strategy for selectively loading Ru NDs onto the Ti_3−xC₂T_y (TC) surface of 2D TC/g-C₃N₄ (CN) heterojunction based on the reductive Ti vacancy defects creatively increased during the preparation of TC/CN by reducing calcination. Notably, the optimized Ru/TC/CN photocatalyst exhibits an outstanding H₂ evolution rate of 3.21 mmol·g⁻¹·h⁻¹ and a high apparent quantum efficiency of 30.9% at 380 nm, which is contributed by the unidirectional transfer of the photogenerated electrons from CN to Ru active sites (CN → TC → Ru) and the suppressed backflow of electrons from Ru sites to CN, as revealed by comprehensive characterizations and density functional theory (DFT) calculations. This work provides a novel strategy for synthesizing the highly efficient photocatalysts with a controllable charge transfer paths, which will boost the development of photocatalysis.