<p>Electric breakdown strength, fatigue resistance, and low temperature sintering are key parameters that strongly influence the energy-storage performance of high-power-density dielectric capacitors. In this work, a series of lead-free perovskite ceramics with the general composition (Ba₀.₈₅Bi₀.₀₆Mg₀.₀₆Ti₀.₉₅Zr₀.₀₅)O₃ (BBMTZ) were synthesized via a conventional solid-state reaction route. To effectively reduce the sintering temperature without degrading electrical performance, a glass–ceramic phase of (Ba₀.₉B₀.₁)TiO₃ (BBT) was incorporated, which was prepared using the melt-quenching technique from calcined BBT powder. X-ray diffraction analysis confirmed the formation of a pure tetragonal phase upon the addition of glass. Dielectric studies revealed excellent thermal stability of permittivity above 180&#xa0;°C, low dielectric loss (&lt; 0.05), and high electrical resistivity, indicating their potential for high-temperature applications. Impedance spectroscopy demonstrated that the composition containing 5&#xa0;mol% BBT exhibited the highest grain resistance (Rg), resulting from the enhanced resistivity mismatch between grains and grain boundaries, which suppressed charge carrier localization and reduced interfacial polarization. At an applied electric field of 50&#xa0;kV/cm, the 5&#xa0;mol% BBT composition achieved a recoverable energy storage density (<i>W</i>_rec) of 145&#xa0;mJ/cm³ with an efficiency (<i>η</i>) of about 90%. These findings highlight that introducing a BBT glass phase provides a simple and effective route to lower the sintering temperature and simultaneously enhance the energy-storage performance of BBMTZ-based dielectric ceramics.</p>