In this work, electrodeposition is proved to be a promising method to prepare Y2O3:Eu3+ thin-film phosphors. The photoluminescence (PL) property of the Y2O3:Eu3+ thin-film phosphor strongly depends on different factors such as the crystal structure of host materials, annealing temperature, and doping concentration of Eu3+. The best PL performance of the Y2O3:Eu3+ thin-film phosphor is achieved for a sample annealed at 600 degrees C with a Eu3+ doping concentration of 1.85 atom %.