Abstract Lead-free (0.94 − x)Na 0.5K 0.5NbO 3– xBiNiO 3–0.06LiSbO 3 piezoelectric ceramics have been sintered at 1105 °C by ordinary solid mixed oxide method. The phase transitional behavior and various electrical properties were investigated. All samples are typical ABO 3 style perovskite structure. A morphotropic phase boundary between orthorhombic and tetragonal ferroelectric phases has been identified in the composition range of 0.002 ≤ x ≤ 0.004. Main piezoelectric parameters of these ceramics were optimized around x = 0.002 with an enhanced piezoelectric constant d 33 of 240 pC N −1, a planar electromechanical coefficient k p of 44%, a mechanical factor Q m of 38, and a Curie temperature T c of 360 °C. These results indicate the materials studied have a promising future in a wide range of applications.