Red-emitting La2MgGeO6:Mn4+ and α-Al2O3:Mn4+ phosphors were synthesized by a polymerized complex method and a novel flux method, which is named as a “combination flux method”, respectively. By using their methods, these phosphors could be successfully synthesized at less than 400°C compared with the conventional solid-state reaction method. In addition, the emission intensity of these phosphors was extremely increased 118 and 2100% compared with the conventional solid-state reaction method. The polymerized complex and the combination flux method are suitable for the enhancement of emission efficiency and low temperature synthesis in Mn4+-activated phosphors.