In this study, we employed the conventional solid-state reaction method to prepare high Curie temperature (Tc) lead-free piezoelectric ceramics by co-doping W6+ and Mn2+ into CaBi2Nb2−x(W3/4Mn1/4)xO9 (designated as CBNWM-x, with 0 ≤ x ≤ 0.08), and our focus was to enhance the electric properties, while maintaining a high Tc. The co-doping of W6+ and Mn2+ into CBN ceramics yields improved DC resistivity (ρDC) and reduced dielectric losses, and leads to a significant enhancement in piezoelectric activity and ferroelectric polarization. In particular, CaBi2Nb1.94(W3/4Mn1/4)0.06O9 is highlighted as the most promising composition, exhibiting remarkable electric properties including a d33 value of 15.2 pC/N, a high Tc of 916.1 °C, a low dielectric loss (tanδ) of 2.7% (at 500 °C), a ρDC value of 8.47 × 106 Ω cm (at 450 °C), and a remanent polarization (Pr) of 11.0 µC/cm2. Notably, even after annealing at 900 °C for 30 min, the d33 value remains at 14 pC/N. The great performance improvement and good thermal stability show that CBN ceramics have promising applications in the field of high-temperature piezoelectric devices.