A series of Ce3+, Eu2+ singly doped and Ce3+/Eu2+ codoped γ-AlON phosphors have been synthesized via a gas-pressure sintering method. The crystal structure, photoluminescence spectra, decay behavior, energy transfer mechanism as well as color chromaticity properties of γ-AlON:Ce3+,Eu2+ were investigated for the first time. A significant spectral overlap between the emission spectrum of γ-AlON:0.025Ce3+ (λex = 285 nm) and excitation spectrum of γ-AlON:0.004Eu2+ (λem = 400 nm) can be observed, indicating the possibility of the energy transfer from Ce3+ to Eu2+, which is further proved by the investigations of emission spectra and flourescence lifetime decay curves. The energy transfer efficiency reaches the maximum of 55.44% calculated basing on decay lifetimes. The energy transfer mechanism was determined to be electric dipole–dipole interaction. The critical distance of energy transfer has been calculated by the concentration quenching method. The results indicated that Ce3+ and Eu2+ activated γ-AlON phosphor could be regarded as good candidates for blue components in full spectrum LEDs.