Red-emitting Gd2O2S:Eu3+ nanophosphors were successfully prepared using a microwave irradiation method followed by hydrogenation treatment. The optimum calcination temperature (900 ºC) was determined by thermogravimetric-differential scanning calorimetry. The X-ray diffraction results showed that all the samples consisted of the pure hexagonal Gd2O2S:Eu3+ phase. The field emission scanning electron microscopy images showed that the Gd2O2S:Eu3+ nanophosphors were spherical, and their average particle diameter increased parallel with the microwave irradiation power. The photoluminescence spectra (under 325-nm excitation) of the samples exhibited red emission corresponding to the 5D0→7F2 transition of Eu3+ ions. A Gd2O2S:Eu3+ nanophosphor screen film was fabricated using the particle-binder sedimentation method. The result shows that the luminance of the Gd2O2S:Eu3+ nanophosphor screen film increased with an increase in the X-ray energy. Hence, this film would become one of the potential candidate for future imaging applications.