CaBi₄Ti₄O₁₅ (CBT)-based Aurivillius high-temperature piezoceramics with different Sb-Mn co-doping amounts were synthesized via the conventional sintering technique. The influences of doping amount on the product were studied via their crystal structure, microstructure, and piezoelectric performance. It is found that an appropriate Sb-Mn co-doping amount can effectively optimize the crystal structure and decrease the oxygen vacancy concentration in CBT ceramics, leading to enhanced electrical properties. Optimized electrical performance with a high Curie temperature (T_C) of 792 °C and a remarkable piezoelectric coefficient (d₃₃) of 25 pC/N were achieved at a doping amount (x) of 0.05. Furthermore, this ceramic is found to exhibit an excellent thermal stability, with d₃₃ retaining 88% of its original value after annealing at 600 °C for 2 h. Moreover, this ceramic shows a high electrical resistivity (ρ) of 1.35×10⁸ Ω·cm with a small dielectric loss (tan δ) of 1.7% at 400 °C. Because of such outstanding piezoelectric performance, it is believed that these Sb-Mn co-doped CBT ceramics could be potential candidates for high-temperature piezoelectric applications.