BiGaO₃ doped BiFeO₃–BaTiO₃ ceramics were prepared by the traditional solid-phase synthesis process. The phase analysis, microstructure, piezoelectric, ferroelectric, dielectric properties, and thermal stability of 0.7BiFeO₃-(0.3 − x)BaTiO₃-xBiGaO₃ (Abbreviated as BF–BT-xBG) were investigated. The results show that the ceramics have rhombohedral (R) and tetragonal (T) structures. Particle dimensions gradually get bigger with the increase of BiGaO₃ concentration, and dense ceramic grains were observed through SEM. Electrical properties of BF–BT-xBG are improved after adding a small amount of BiGaO₃: piezoelectric constants d₃₃ = 141 pC/N, electromechanical coupling coefficient k_p = 0.314, mechanical Quality Factor Q_m = 56.813, dielectric loss tanδ = 0.048, residual polarization intensity P_r = 18.3 µC/cm², Curie temperature T_c = 485.2 °C, depolarization temperature T_d = 465 °C for x = 0.003. The “temperature-piezoelectric performance” curve under in situ d₃₃ indicates that piezoelectric properties d₃₃ increase rapidly with increasing temperature. Remarkably, the piezoelectric response d₃₃ reaches a maximum of 466 pC/N at a temperature T = 340 °C, and afterward, reduces gradually to zero with increasing temperature until 450 °C.