Improving the osteoconductive potential of titanium implants has been of continuing interest in the fields of dentistry and orthopedic surgery. This study determined the bioactivity of ultraviolet (UV) light-treated titanium. Human mesenchymal stem cells (MSCs) were cultured on acid-etched microtopographical titanium surfaces with and without 48 h pretreatment with UVA (peak wavelength of 360 nm) or UVC (peak wavelength of 250 nm). The number of cells that migrated to the UVC-treated surface during the first 3 h of incubation was eight times higher than those that migrated to the untreated surface. After 24 h of incubation, the number of cells attached to the UVC-treated surface was over three times more than those attached to the untreated surface. On the UVC-treated surface, the cellular spread was expedited with an extensive and intensive expression of the focal adhesion protein vinculin. The cells on the UVC-treated surface exhibited a threefold higher bromodeoxyuridine incorporation, a doubling of the alkaline phosphatase-positive area and the up-regulated expression of bone-related genes, indicating the accelerated proliferation and differentiation. The UVC-treated surface did not adversely affect the viability of the cells. These biological effects were not seen after UVA treatment, despite the generation of superhydrophilicity. Thus, we discovered a novel photofunctionalization of titanium dioxide that substantially enhances its bioactivity in human MSCs. Further studies are required to investigate the universal effectiveness of this surface modification for different titanium-containing materials, with varying chemistries and textures, as well as to understand its significance in enhancing in vivo osteoconductivity.