The energy transfer and multiple photoluminescence of LuNbO4:Eu3+,Tb3+ powders were investigated. The photoluminescence spectra of the powders mainly consisted of green and red emission peaks. The green emission peaks (551 nm) were assigned to the D-5(4) -> F-7(5) transition of Tb3+, and the strong red emission peaks (614 nm) originated from Eu3+ (D-5(0) -> F-7(2)) via a Tb3+ -> Eu3+ energy transfer. Tb3+Eu3+ co-doping greatly enhanced the red emission under UV excitation that could rarely activate Eu3+ ions. The emission of the powders was tunable from green to red by adjusting the ratio of Eu3+/Tb3+, and thus warm white-light-emitting powders could be obtained. The Tb3+ -> Eu3+ energy transfer mechanism was explained using the energy transfer efficiency, the critical distance for the Tb3(+) -> Eu3+ energy transfer, fluorescence decay curves, and multipolar interactions. The results demonstrate that (LuNbO4Eu3)-Eu-:+,Tb3+ powders have a high potential for use in UV-pumped white-light-emitting diodes.