In this study, (1-x)(Na_0.52K_0.443Li_0.037)(Nb_0.883Sb_0.08Ta_0.037)O₃-x(Bi_0.5(Na_0.7K_0.3)_0.5ZrO₃ ceramics were fabricated by BNKZ substitution using a conventional solid-state method to develop excellent lead-free piezoelectric ceramics for piezoelectric actuators; their dielectric and piezoelectric properties were then investigated. All specimens were in the orthorhombic phase. NKL-NSTO₃ ceramics with x=0.01 showed excellent piezoelectric properties. The density (ρ), piezoelectric charge constant (d₃₃), planar piezoelectric coupling coefficient (k_p), mechanical quality factor (Q_m), and dielectric constant (ε_r) had optimized values of 4.56 g/㎤, 208 pC/N, 0.43, 96, and 975, respectively.