Abstract <p>Dielectric energy storage materials play a pivotal role in pulsed power systems. In this work, ternary, quaternary, and quinary BiMeO₃-doped BaTiO₃ ceramics were systematically constructed, and the influence of B-site diversification on the microstructure, polarization mechanism, and energy storage performance was investigated. The results indicate that increasing configurational entropy modifies the local random fields and polarization response of the system, while simultaneously overriding the dominant contribution to polarization from individual elements, leading to an averaged and stabilized polarization response. Finally, through multi-scale comparative analysis, a quinary composition exhibiting both excellent room-temperature energy storage performance (<i>W</i>_rec = 6.7&#xa0;J&#xa0;cm⁻³, <i>η</i> = 94%) and superior temperature stability (−85–220 ºC, Δ<i>W</i>_rec ~  ± 9%, Δ<i>η</i> ~  ± 4.8%) is identified. This study highlights the critical role of B-site compositional diversity in dielectric ceramics and establishes a generalizable design principle for high-performance energy storage ceramics via entropy engineering.</p> Graphical abstract <p>In this work, ternary, quaternary, and quinary BiMeO₃-doped BaTiO3 ceramics were systematically constructed, and the influence of B-site diversification on the microstructure, polarization mechanism, and energy storage performance was investigated. The results indicate that increasing configurational entropy modifies the local random fields and polarization response of the system, while simultaneously overriding the dominant contribution to polarization from individual elements, leading to an averaged and stabilized polarization response. Finally, through multi-scale comparative analysis, a quinary composition exhibiting both excellent room-temperature energy storage performance (Wrec=6.7 J cm^-³, η=94%) and superior temperature stability (-85-220 ºC , ΔWrec ~±9 %, Δη ~ ±4.8%) is identified.</p>