We introduce a facile fabrication process for ultrathin nitrogen-doped graphene quantum dot (NGQD) layers on TiO2 nanoparticles in order to develop high-performance photocatalysts. NGQDs are grown either by graphitization of precursors or direct deposition of premade NGQDs. Photocatalytic performance is shown to be dependent on the thickness of NGQD layers and doping levels of C and N atoms on TiO2 surfaces. The nanocomposites shown to absorb a broad range of visible light and narrow the bandgap by 0.38 eV, resulting in the increased density of photoinduced eletron-hole pairs and efficient charge separation at the interface between the NGQDs and TiO2.