The environmentally-friendly (1-x)Ba(Zr_0.1Ti_0.9)O₃-xBa(Mg_1/3Ta_2/3)O₃ (x=0, 0.02, 0.04, 0.06, 0.08) relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1400 °C for 2 h. SEM and XRD analyses were utilized to study the surface morphologies and the crystalline structures, respectively. The effects of Ba(Mg_1/3Ta_2/3)O₃ on the phase transformation, dielectric and ferroelectric properties of Ba(Zr_0.1Ti_0.9)O₃ ceramics were also investigated. It is found that the average grain size of (1-x)Ba(Zr_0.1Ti_0.9)O₃-xBa(Mg_1/3Ta_2/3)O₃ (BZT-BMT) perovskite single-phase ceramics decreases as the content of Ba(Mg_1/3Ta_2/3)O₃ (BMT) increases. The relaxor ferroelectric behavior with diffuse phase transition and well-defined frequency dispersion of dielectric maximum temperature is found for the ceramic with increasing x values. 0.98BZT-0.02BMT ceramic shows very good dielectric properties with the relative permittivity and the dielectric loss, measured at 100 kHz as 6034 and 0.01399 respectively at room temperature. Both remnant polarization and coercive field decreased with increasing BMT content, indicating a transition from the ferroelectric phase to the paraelectric phase at room temperature.