The requirement of using ultraviolet light to stimulate afterglow luminescence has seriously restricted indoors/outdoors applications of most persistent materials developed hitherto. Herein, efficient blue-light-activated Ce3+, Pr3+: YAGG phosphors, showing optimized long-persistent luminescence lasting for 1 h, were prepared and investigated in detail with the aid of X-ray diffraction refinement, steady-state/persistent photoluminescence spectra, room/low-temperature persistent decay curves, and three-dimensional thermo-luminescence spectra. Notably, the afterglow properties were found highly dependent on the Ga content which greatly alters both the host band gap energy and the Ce3+: 5d level structure and thus is beneficial to the electrons' photoionization and trapping processes. Moreover, Pr3+ additive was found not only prolonged the afterglow lifetime of Ce3+ through improving concentration of carriers captured at the trap, but also served as the red-emissive centers for color tuning. The persistent energy transfer from Ce3+ to Pr3+ was experimentally demonstrated for the first time.