Ho3Fe5O12 ceramics were fabricated by the solid-state reaction method. The results revealed an increase of the grain size, dielectric constant, and dielectric loss, while a decrease of the remnant magnetization and coercive field with increasing sintering temperature. A dielectric relaxation behavior was observed, which might be associated with the charge carrier hopping between Fe2+ and Fe3+. A cole–cole fitting to loss peaks revealed a dependence of the activation energy and the broaden factor on the relative density of the samples. Furthermore, at appropriate frequencies, the 1250 °C-sintered samples showed high dielectric constant, low dispassion, and good temperature stability around room temperature.