A series of undoped and Eu³⁺ doped YOF and Y_1−xGd_xOF (x = 0–0.7) crystals were prepared via a urea based homogeneous precipitation method followed by a heat treatment process. After Gd³⁺ doping, we observed the crystal phase transition, morphology transformation, and greatly enhanced luminescence properties of the YOF crystals. The results reveal that the addition of Gd³⁺ can promote the phase transition from the hexagonal phase to the rhombohedral phase and the morphology transformation from spheres, though a mixture of rods and spheres, to spheres. The luminescence properties of Eu³⁺ doped YOF phosphors were investigated upon UV excitation and the quenching concentration of Eu³⁺ was found to be 10 mol%. More importantly, the luminescence intensity after doping a certain amount of Gd³⁺ increased by 31 times compared to that of the Gd³⁺ free sample, which may be due to the modification of the crystal field and the crystal phase of YOF, providing an effective way to gain numerous Gd³⁺ doped luminescent materials. These results show that the Gd³⁺ doped red phosphors have potential applications in white light emitting diodes.