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≥7.26wt%. • TC shifts to lower temperature with the substitution of the Ti-site by Zn2+ and Nb5+ in BT system. • Pr 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=7.26wt%, exhibiting a maximum energy storage capability.