Quantum dots (QDs) are attractive alternatives for organic phosphors in light emitting diodes (LEDs) due to their high quantum yield and photostability. Various methods have been developed for fabrication of LEDs using QDs, yet the reduction in quantum yield during film formation still limits their practical applications. We prepared hybrid particles by coating spherical poly(methyl methacrylate) (PMMA) particles with the CdSe/ZnS QDs, and dispersed them in the PMMA matrix. The PMMA particles were derived from the same material as the PMMA matrix, so that they could not only act as a spacer but also match the refractive index between the polymer particles and matrix. The PMMA@QD hybrid particles exhibited higher quantum yield in both suspension and film states than the pristine QDs. In addition, the dispersion state of QDs in PMMA matrix was significantly improved by using the hybrid particles. Finally, it was demonstrated that the QD-based LED device containing the PMMA@QD hybrid particles exhibited enhancement in both color conversion and luminous efficiencies.