Gd2O2S:Ln(3+) (Ln = Eu, Tb) submicrospheres were successfully prepared through a facile and mild solvothermal method followed by a subsequent heat treatment. X-ray diffraction (XRD) results demonstrate that all the diffraction peaks of the samples can be well indexed to the pure hexagonal phase of Gd2O2S. The energy dispersive spectroscopy (EDS), element analysis, and FT-IR results show that the precursors are composed of the Gd, Eu, O, S, C, H, and N elements. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show that these spheres are actually composed of randomly aggregated nanoparticles. The formation mechanism for the Gd2O2S:Ln(3+) (Ln = Eu, Tb) spheres has been proposed on an isotropic growth mechanism. Under ultraviolet excitation Gd2O2S:Ln3+(Ln = Eu, Tb) spheres show red and green emission corresponding to the D-5(0)-> F-7(2) transition of the Eu3+ ions and the D-5(4)-> F-7(5) transition of the Tb3+ ions. Furthermore, this synthetic route may have potential applications for fabricating other lanthanide oxysulfides.