The rapid recombination rate of photogenerated carriers in TiO has been limiting the photocatalytic performance. Herein, TiO thin flakes modified by g-CN quantum dots (g-CN QDs) were fabricated successfully through a facile thermal treatment of restacked single-layer nanosheets of TiO in the presence of urea as a source of g-CN QDs. Characterizations showed that g-CN QDs with a size of ~10 nm were homogeneously deposited on the surface of TiO thin flakes. Quenching experiments of •OH radicals and the detection of radicals by EPR certified the direct Z-scheme heterojunctions between g-CN QDs and TiO flakes. The TiO nanoflakes/g-CN QDs hybrid exhibited excellent activity for the photocatalytic hydrogen evolution from a methanol solution and the degradation of RhB due to the enhanced charge separation efficiency and improved light absorption in the direct Z-scheme heterojunctions. This study demonstrates that the rational design of heterojunction is effective for attaining the superior photocatalytic performance.