Carbon dot and BiVO quantum dot composites (CDs/BiVO QDs) show a significantly improved photocatalytic activity and high stability for overall water splitting. By using 5% CDs/BiVO QDs as photocatalysts, the H evolution of 0.92 μmol h, was achieved under solar light irradiation without any cocatalysts or sacrificial reagents, which is about 4 times that of BiVO QDs (0.21 μmol h). Note that, for the CD/BiVO QD catalyst, the produced H and O are approximately equal to the stoichiometric ratio (H : O = 1.80 : 1), while that of BiVO QDs is nonstoichiometric (about only 0.06 : 1). In addition, the present water splitting occurs via a two-electron pathway and CDs and BiVO QDs served as the reduction and oxidation reaction active sites, respectively.