Materials with high insulating composition of (1–x)Bi0.47Na0.47Ba0.06TiO3–xBaZrO3 abbreviated as (NBBT–xBZ) (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) and NBBT–0.04BZ–z%BBS (0.96Bi0.47Na0.47Ba0.06TiO3–0.04BaZrO3; z wt%BaO–B2O3–SiO2) (z = 20, 30, 40, 50) were prepared by using a conventional, solid-state reaction route. X-ray diffraction analysis of the samples revealed that the crystal structure was a pseudo-cubic structure with change of unit cell. Effects of BZ (BaZrO3) and further BaO–B2O3–SiO2 (BBS) content on the microstructures, phase evolution, dielectric properties, breakdown characteristics, and discharged energy storage were investigated, respectively. In pace with the raising of BZ amount, the grain size of the ceramics increased, and the permittivity of dielectric and dielectric loss decreased. Dielectric relaxation behaviors were observed in dielectric constant versus temperature plots. The breakdown strength showed a trend of first increase and then decrease with the increase of BZ. Furthermore, adding enough BBS additive resulted in an ascent of energy–storage capability and an enhancement of energy efficiency. As a result, the improved structure of NBBT–xBZ ceramics resulted in an increase of up to 62 % in the breakdown strength, yielding an enhanced discharged energy density of 0.883 J/cm3 which were achieved from 80 kv/cm at x = 4 mol%, and an energy density of 1.05 J/cm3 was generated at an electric field of 110 kV/cm of NBBT–0.04BZ–z%BBS (z = 40) glass ceramic.