3 Lead-free piezoelectric ceramics, 0.96[{Bi 0.5 (Na 0.84 K 0.16) 0.5 } 1 – x Li x (Ti 1 – y Nb y)O 3 ]–0.04SrTiO 3 (BNKLiTN– ST) with x, y = 0–0.030, were synthesized by solid-state reaction method. X-ray diffraction patterns indicated that Li and Nb successfully diffused into the BNKT–ST lattice and formed a pure perovskite structure with x ≤ 0.025. Increasing the Li and Nb contents (x,y = 0.020) induced a phase transformation from the coexistent rhombohedral–tetragonal phases for pure BNKT–ST ceramics to a pseudocubic phase, resulting in degradation of the remnant polarization and coercive field. However, the field-induced strain was markedly enhanced at x, y = 0.020, giving rise to a giant dynamic piezoelectric constant (d 33 * = S max /E max = 800 pm/V). Furthermore, the temperature dependence of the field-induced strain response showed temperature insensitivity up to 120°C. To explore its potential for device applications, a 10-layered stack-type multilayer actuator was fabricated from the optimal composition (x, y = 0.020). This actuator showed a large S max /E max of 600 pm/V at a relatively low driving field of 4.5 kV/mm suggesting highly promising results in lead-free BNT-based ceramics.