A comprehensive study on energy harvesting characteristics as well as electro‐mechanical properties of lead‐free (1−x)(BaZr0.2Ti0.8)O3—x(Ba0.7Ca0.3Ti)O3 ceramics were systematically carried out. Raman and Rietveld analyses show a formation of rhombohedral‐orthorhombic‐tetragonal (R‐O‐T) phase boundary region between 4/6 BZT/BCT and 6/4 BZT/BCT compositional range. Raman modes shift toward lower frequencies with increased Zr/Ca stoichiometric ratio attributed to asymmetric Ti‐O phonon vibrations, which caused local disorder, widening of energy band and reduced Curie temperature. The large mechanical quality factor Qm = 556 is related to the hardening effect and significantly high energy conversion efficiency η = 96% was discovered for 3/7 BZT/BCT composition. Largely, the noblest electro‐mechanical properties were retrieved for 5/5 BZT/BCT ceramics, in which d33 = 500 pC/N (from quasi‐static d33 meter), d33 = 540 pm/V (from field‐dependent d33 curves) indicating that the both methods are analogous with a deviation of 8%. The outstanding energy harvesting characteristics such as voltage constant g33 = 27 × 10−3 Vm/N, transduction coefficient d33 × g33 = 13 301 × 10−15 m2/N, figure of merit under off‐resonance conditions FOMoff = 12.1 × 10−10 m2/N and fairly large η of 94% were attained again for 5/5 BZT/BCT ceramics. These outstanding characteristics were ascribed to the R‐O‐T phase boundary region that comprises a low energy barrier, consequently facilitated easy polarization rotation and triggered an increased electro‐mechanical conversion. These characteristics outperform other lead‐free and even most commercially available lead‐based ceramics, and thus suitable for sensors, actuators, resonators, and energy harvesting applications. [ABSTRACT FROM AUTHOR]