<p>Piezoelectric materials are among the most essential functional materials, with widespread applications across various fields. As the demands of industries such as aerospace continue to evolve, the need for high-temperature piezoelectric materials has become more critical. Bismuth layer-structured ferroelectric (BLSF) bismuth titanate-ferrite (Bi₅Ti₃FeO₁₅), is a typical bismuth-layered piezoelectric compound, known for its high Curie temperature (<i>T</i>_C ~ 761°C). Despite its promising properties, the application of Bi₅Ti₃FeO₁₅ at elevated temperatures is hindered by issues such as a low piezoelectric constant and poor direct-current (dc) electrical resistivity. In this study, we report a significant enhancement in the piezoelectric properties of Bi₅Ti₃FeO₁₅ at high temperatures through the co-substitution of sodium (Na) and cerium (Ce) into the Bi₅Ti₃FeO₁₅ lattice. The crystal structure, microstructure, and dielectric, electrical, ferroelectric, and piezoelectric properties of Bi_5−<i>x</i>(NaCe)_<i>x</i>/2Ti₃FeO₁₅ (BTF-100<i>x</i>NaCe), were thoroughly investigated. Our results reveal that the piezoelectric constant (<i>d</i>₃₃) of BTF-14NaCe is significantly improved, reaching 22.8 pC/N, which is three times that of pristine Bi₅Ti₃FeO₁₅ (7.1 pC/N), while the <i>T</i>_C remains nearly unchanged at approximately 760°C. Furthermore, BTF-14NaCe exhibits significantly enhanced high-temperature dc electrical resistivity, with values of 1.93 × 10⁷ Ω·cm at 400°C and 1.28 × 10⁶ Ω·cm at 500°C, nearly two orders of magnitude higher than those of Bi₅Ti₃FeO₁₅ (6.98 × 10⁵ Ω·cm at 400°C, 7.63 × 10⁴ Ω·cm at 500°C). Additionally, BTF-14NaCe demonstrates remarkable thermal stability of both piezoelectric and electromechanical properties up to 400°C. These findings indicate that the Bi₅Ti₃FeO₁₅-based ceramic material holds considerable potential as an advanced candidate for high-temperature piezoelectric applications.</p>