In the present work, highly dense complex perovskite oxide ceramics with the formula of (1-x)[Bi0.5(Na0.80K0.20)0.5TiO3-0.005LiNbO3]-x(Ca3Co4O9) or (1-x)[BNKT-0.005LN]-xCCO, where x = 0, 0.010, 0.015, 0.020 and 0.025 mol fraction were fabricated by a solid-state mixed oxide method. After sintering at 1125 °C for 2 h, all ceramics were characterized in terms of physical, phase evolution, microstructure, dielectric, ferroelectric, and piezoelectric properties. XRD patterns of all samples indicated single phase of perovskite structure with good relative density value of ∼ 97 − 98%. The SEM image indicated that cubic-like shaped grains were observed in all samples. The average grain size was found to increase with increasing the modifier content. Optimum electrical properties (i.e. εr = 1485, tanδ = 0.0460, Pr = 13.13 µC/cm2, Ec =14.92 kV/cm and d33 = 145 pC/N) were found in the sample with x = 0.010 mol fraction.