Dielectric materials with high power density, fast charge and discharge rates, and high energy-storage density are urgently required due to the rapid development of hybrid vehicles and pulse power boosting technology. In this work, the novel environment-friendly (1-x)(Ba0.8Sr0.2)TiO3-xBi(Zn2/3Nb1/3)O3 (0.04 ≤ x ≤ 0.16) (1-x)BST-xBZN ceramics were designed and synthesized by traditional solid-state reaction method, exhibiting ultrahigh energy efficiency and super stability against temperature. The results show that the recoverable energy density (Wrec) and the energy efficiency (η) of the (1-x)BST-xBZN ceramics are increase sharply then decrease slightly with increasing of x value. The 0.88BST-0.12BZN ceramic demonstrated a recoverable energy density of ≈ 1.62 J/cm3 and an extreme high energy efficiency of ∼ 99.8 % at 225 kV/cm at room temperature. These extreme high efficiency and high breakdown strength would make (Ba,Sr)TiO3-based lead-free ceramic systems might be good candidate for high power energy-storage applications pulsed power systems.