In this work, (1$-x$)(0.92NaNbO₃–0.08BaTiO₃)–$x$Ca${}_{0.7}$La${}_{0.2}$TiO₃ (NNBT –$x$CLT) ceramics were successfully designed and prepared by the solid-state reaction method. Investigations on the structure, dielectric, and energy storage properties were performed. The NNBT – 0.25CLT ceramic with orthorhombic phase at room temperature was found to exhibit extremely small grain size and compacted microstructure. A large$W_{\mathrm{\text{rec}}}$ of 3.1 J/cm³ and a high$\eta$ of 91.5% under the electric field of 360 kV/cm were achieved simultaneously in the sample. In addition, the energy storage performance of the sample exhibits thermal stability over the temperature range of 25–140${}^{\circ }$C and the frequency range of 5–500 Hz. The charge and discharge tests reveal that the ceramic shows a large current density$C_D$ of 965 A/cm² and power density$P_D$ of 154 MW/cm³. This work demonstrates that the NNBT–0.25CLT ceramic is a prospective energy storage material for potential application in the field of pulsed power devices.In this work, (1$-x$)(0.92NaNbO₃–0.08BaTiO₃)–$x$Ca${}_{0.7}$La${}_{0.2}$TiO₃ (NNBT –$x$CLT) ceramics were successfully designed and prepared by the solid-state reaction method. Investigations on the structure, dielectric, and energy storage properties were performed. The NNBT – 0.25CLT ceramic with orthorhombic phase at room temperature was found to exhibit extremely small grain size and compacted microstructure. A large$W_{\mathrm{\text{rec}}}$ of 3.1 J/cm³ and a high$\eta$ of 91.5% under the electric field of 360 kV/cm were achieved simultaneously in the sample. In addition, the energy storage performance of the sample exhibits thermal stability over the temperature range of 25–140${}^{\circ }$C and the frequency range of 5–500 Hz. The charge and discharge tests reveal that the ceramic shows a large current density$C_D$ of 965 A/cm² and power density$P_D$ of 154 MW/cm³. This work demonstrates that the NNBT–0.25CLT ceramic is a prospective energy storage material for potential application in the field of pulsed power devices.