DUV and VUV light emitters have a variety of applications, such as in ozone cleaners, UV sterilization, etc. Rocksalt-Structured (RS) MgZnO alloys have attracted much attention as candidate materials for the solid-state DUV and VUV emitters. In this study, successful growths of atomically-flat single crystalline RS-MgZnO films on (001) MgO substrates by the mist chemical vapor deposition method and observation of DUV emission were demonstrated. Further improvements in its crystalline quality resulted in the predominate observation of cathodoluminescence (CL) peak at around 199-210 nm. The CL spectra showed relatively high equivalent internal quantum efficiencies of 2.5–11% for the DUV near-band-edge emission.