We report on a vertical geometry Mott-type visible (VIS)-blind Ultraviolet (UV) photodetector which was fabricated based on wurzite MgZnO (W-MgZnO) with a cubic MgZnO (C-MgZnO) anti-reflection layer. The C-MgZnO layer plays two roles in the detector, not only the conventional optical part but also electrical part. Photon-generated holes were restricted due to valence band offset. More “hot” electrons injected over a reduced Mott potential barrier at the metal-semiconductor interface, resulting in additional current contributing to photoresponse. This dual-function structure is a highly compact and wavelength-resonant UV detector, with a spectral response high-gain and fast.