Bandgap engineering by doping and co-catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible-light absorption and charge separation, respectively. Shifting of the TiO2 conduction band edge is frequently applied to increase visible-light absorption but also lowers the reductive properties of photo-excited electrons. Herein, we report a visible-light-driven photocatalyst based on valance band edge control induced by oxygen excess defects and modification with a CuxO electron transfer co-catalyst. The CuxO grafted oxygen-rich TiO2 microspheres were prepared by ultrasonic spray pyrolysis of the peroxotitanate precursor followed by a wet chemical impregnated treatment. We found that oxygen excess defects in TiO2 shifted the valence band maximum upward and improved the visible-light absorption. The CuxO grafted onto the surface acted as a co-catalyst that efficiently reduced oxygen molecules to active intermediates (i.e., O2·– radial and H2O2), thus consuming the photo-generated electrons. Consequently, the CuxO grafted oxygen-rich TiO2 microspheres achieved a photocatalytic activity respectively 8.6, 13.0 and 11.0 as times high as those of oxygen-rich TiO2, normal TiO2 and CuxO grafted TiO2, for degradation of gaseous acetaldehyde under visible-light irradiation. Our results suggest that high visible-light photocatalytic efficiency can be achieved by combining oxygen excess defects to improve visible-light absorption together with a CuxO electron transfer co-catalyst. These findings provide a new approach to developing efficient heterojunction photocatalysts.