In order to meet the requirements of miniaturization and weight reduction for dielectric capacitors, the development of ferroelectric ceramics with high energy storage density has become a research focus. In this work, (1 - x) Ba0.85Ca0.15Zr0.08Ti0.92O3-xSm(2)O(3) (BZCT-xSm) lead-free ceramics were synthesized using a traditional solid reaction method, and the microstructure, ferroelectricity, and energy storage properties of BZCT ceramics doped with Sm2O3 were systematically studied. After the introduction of Sm3+, all ceramics possess a pure perovskite structure, and the average grain size of the ceramics is greatly reduced. Because the substitution of Sm3+ at the A-site destroys the long-range order of ferroelectric domains, the P-E hysteresis loop changes from a rectangular shape to a needle shape, which promotes the improvement of energy storage properties. Notably, the BZCT-0.03Sm ceramics exhibit the large energy storage density (W) of 0.94 J/cm(3) and ultra-high energy storage efficiency of 95.1%.