Large-area (>1 cm2), vertically aligned ZnGa2O4, Mn2+ doped ZnGa2O4 (ZnGa2O4:Mn2+) and Cr3+ doped ZnGa2O4 (ZnGa2O4:Cr3+ ) nanowire arrays were synthesized by a two-step thermal evaporation method using ZnO nanowire arrays as the templates followed by reaction with Ga and/or dopant (Mn or Cr) vapors. Bright red, green, and blue luminescence was achieved, respectively, from ZnGa2O4:Cr3þ, ZnGa2O4:Mn2þ, and ZnGa2O4 nanowire arrays under ultraviolet light irradiation. The realization of three primary colors from one host material suggests that full color display based on ZnGa2O4 nanowires might be achievable.