Lead-free piezoelectric ceramics have attracted considerable attention owing to their environmental friendliness and good electrical properties. Here the new (1 − x)K_0.5Na_0.5NbO₃–x(0.15Bi_0.5Na_0.5TiO₃–0.85Bi_0.5Na_0.5ZrO₃) [(1 − x)KNN–x(BNT–BNZ)] ternary lead-free piezoelectric ceramics synthesized by conventional solid sintering method are reported. The microstructure and electrical properties of (1 − x)KNN–x(BNT–BNZ) ternary ceramics were systematically investigated, and the ceramics with x = 0.06 possess enhanced piezoelectric properties and a high T_C (e.g., d₃₃ ∼ 318 pC N⁻¹, k_p ∼ 0.43, and T_C ∼ 326 °C), which are mainly ascribed to the R–T phase boundary involved. It is believed that, such a ceramic system is a promising candidate in the field of lead-free piezoelectric ceramics.