ZnO-based photodetectors (PDs) have a small on/off ratio and long response time, which hamper their practical UV detection. Herein, a facile method to prepare a nanodiamond (ND)-decorated ZnO nanowire (ZNW) ultraviolet photodetector was demonstrated. This hybrid ZnO -ND UV photodetector considerably improved photodetection performance compared with bare ZnO. This hybrid device simultaneously exhibited remarkable detectivity, rapid response, and decent current on/off ratio. This excellent performance was attributed to the synergistic effect between NDs and the ZNWs. These results introduce a new scenario for designing and fabricating an innovative optoelectronic system.