K3Gd(PO4)2:Tb3+ phosphors are synthesized by the solid reaction method, and the phases and luminescence properties of the obtained phosphors are well characterized. The emission spectra of K3Gd(PO4)2:Tb3+ exhibit the typical emissions of Tb3+. Concentration quenching of Tb3+ is not observed in K3Gd(PO4)2:Tb3+, likely because the shortest average distance of Tb3+–Tb3+ in K3Gd(PO4)2:Tb3+ is adequately long such that energy transfer between Tb3+–Tb3+ ions cannot take place effectively. This result indicates that K3Tb(PO4)2 phosphors have potential application in near ultraviolet (n-UV)-convertible phosphors for white light-emitting diodes.