Nanocrystalline SrCO3:Tb3+ phosphor layers were coated on monodisperse and spherical polystyrene particles by a typical hydrothermal synthesis without further annealing treatment, resulting in the formation of core-shell-structured polystyrene@SrCO3:Tb3+ particles. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, photoluminescence, as well as lifetimes were employed to characterize the resulting composite particles. Under ultraviolet excitation, the polystyrene@SrCO3:Tb3+ phosphors show the characteristic D-5(4)-F-7 (J) (J = 6, 5, 4, 3) emission lines with green emission D-5(4)-F-7(5) (544 nm) as the most prominent group. The obtained core-shell phosphors are potentially applied in fluorescent lamps.