[en] Highlights: • The BaTiO₃–ZnNb₂O₆ ceramics were prepared by a solid state reaction method. • ZnNb₂O₆ addition lowers sintering temperature, decreases grain size, while introduces second phase (Ba₂Ti₅O₁₂) for x ≥ 7.26 wt%. • T_C shifts to lower temperature with the substitution of the Ti-site by Zn²⁺ and Nb⁵⁺ in BT system. • P_r of BT-based ceramics are decreased effectively by addition of ZnNb₂O₆. • The dielectric breakdown strength is enhanced with the increasing doping level of ZnNb₂O₆ and reaches a maximum value at x = 7.26 wt%, exhibiting a maximum energy storage capability. -- Abstract: BaTiO₃ ceramics were prepared using solid state reaction with addition of ZnNb₂O₆, to investigate the effects of ZnNb₂O₆ addition on structure and properties. The results show that the ZnNb₂O₆ addition lowers sintering temperature, decreases grain size, while introduces second phase (Ba₂Ti₅O₁₂) for x ≥ 7.26 wt%. The dielectric breakdown strength is enhanced with the increasing doping level of ZnNb₂O₆ and reaches a maximum value at x = 7.26 wt%, exhibiting a maximum energy storage capability