(Tb1−xRx)3Al5O12 (R = Y, Ce) magneto-optical transparent ceramics were synthesized by solid state reaction and vacuum sintering. The two-step sintering method was also applied to investigate the properties of the Y3+ doped Tb3Al5O12 samples. The Verdet constant of the Y3+ doped Tb3Al5O12 transparent ceramic measured at 632.8 nm was −108.79 rad · T−1 · m−1, which was smaller than that of the Tb3Al5O12 transparent ceramics. However, the magneto-optical property of the Ce3+ doped Tb3Al5O12 samples was improved a lot. The Verdet constant measured at 632.8 nm was −199.55 rad · T−1 · m−1, which was about 16% larger than that of Tb3Al5O12.