Heterogeneous structures containing highly dispersed semiconductor nanoparticles on a photoactive support are effective for the photocatalytic hydrogen evolution reaction (HER). In this work, the interlayer ion-exchange and space confining nature of layered titanate nanosheets was used to embed copper ions in titanates, which were then transitioned to mesoporous CuxO/TiO2 with highly dispersed CuxO nanostructures. Both experimental and density functional theory (DFT) studies demonstrated that the fine-decoration of CuxO nanostructures and the reducible valence of the copper species enabled stable superior photocatalytic activity. The HER efficiency was enhanced to 12.45 mmol g-1 h-1 for the mesoporous CuxO/TiO2 composites in comparison to an efficiency of 0.38 mmol g-1 h-1 for the non-modified TiO2. Steady HER performances over 10 h, cyclic HER measurement over 60 h, and testing of the composite kept under ambient conditions for over one year, demonstrated excellent stability of the composite against photochemical and wet-chemical erosion.