The Sr2Si1−xGexO4 : Eu2+ phosphors are formed by means of a new synthesis method. The Sr2Si1−xGexO4 : Eu2+ have the mean particle size of 200 nm and the spherical shape. The Sr2Si1−xGexO4 : Eu2+ show two emission colors : the blue color of 480 nm and the green color of 525 nm. The intensity of green band with respect to blue band is significantly decreased in comparison with that of solid-reacted bulk sample, described by the hindrance of the energy transfer between the blue and green band by numerous nanoparticle boundaries. As the increase of Ge4+ ions, the 480 nm emission intensity of the Sr2Si1−xGexO4 : Eu2+ are more dominant. This behavior can be understood in terms of the effect of Ge4+ ions on the energy transfer from 480 nm band to 525 nm band. The fabricated white-light emitting diode using ultraviolet InGaN chip with the blue and green emitting Sr2Si1−xGexO4 : Eu2+ phosphor shows warm white light of 4300 K and higher color stability against input power in comparison with a commercial blue GaN-pumped YAG:Ce3+.