[en] Polycrystalline (1 - x)PLZT-xPBBiN ferroelectric complex ceramic nanocomposites were synthesized through high-energy mechanical activation technique. It is found that milling time has a significant impact on the phase formation, particle size and grain growth. The optimized compositions were subjected to XRD, SEM, dielectric and piezoelectric studies. Powder X-ray diffraction studies revealed that the nanocomposites consisted of both perovskite (tetragonal) and tungsten bronze (orthorhombic) structures whilst pure PLZT showed perovskite structure and pure PBBN showed tungsten bronze structure. As the PBBN content increased, the in situ prepared perovskite and tungsten bronze nanocomposites revealed a bi-phase formation. It is worth mentioning that crack-free nanoceramic composites were obtained. The maximum dielectric constant (ε_RT = 2509), piezoelectric planar coupling coefficient (k_p = 0.584) and the piezoelectric charge coefficient (d₃₃ = 596 pC/N) were observed for x = 0.6 nanoceramic composite. It has been observed that the dielectric and piezoelectric constants increased gradually with increasing x up to 0.6 and was found optimum, which could be ideal for electromechanical and energy harvesting applications.