Improvements in phase stability and dielectric characteristics can broaden the applications of zirconia in ceramics. Herein, a series of Y₂O₃-stabilized zirconia (YSZ) ceramics are synthesized using solid-state sintering, followed by an investigation into their phase evolution, grain size, dielectric constant, and breaking field. As the Y₂O₃ content increases from 0 wt% to 4 wt%, the as-grown YSZ ceramics undergo a distinct phase transformation, transitioning from monoclinic to monoclinic + tetragonal and further to monoclinic + tetragonal + cubic, before finally returning to monoclinic + cubic. Significant changes occur in the internal microstructure and grain size of the ceramics as the phase composition alters, resulting in a reduction in grain size from 3.17 μm to 0.27 μm. Moreover, their dielectric constants exhibit an increasing trend as the Y₂O₃ content increases, rising from 3.92 to 13.2. Importantly, the dielectric breakdown field of these YSZ ceramics shows a similar variation to the phase evolution, ranging from 0.11 to 0.15 MV/cm. This study sheds light on the phase evolution and dielectric properties of YSZ ceramics, offering an efficient strategy for enhancing their dielectric performances.