Dielectric ceramics with high recoverable energy storage density (W-rec) and high energy storage efficiency (eta) are urgently needed due to their potential application in pulse capacitor devices. However, the low eta and breakdown strength (BDS) have produced a bottleneck for achieving high W-rec at high electric field. Here, we introduce Bi(Mg0.5Ti0.5)O-3 (BMT) into Ba(Ti0.92Sn0.08)O-3 (BTS) matrix to enhance the relaxor character of BTS-xBMT and reduce the electrostrictive strain generated during electric field loading. The enhanced relaxor character is beneficial for increasing the efficiency, whereas the reduced electrostrictive strain is profitable to increase the BDS. Furthermore, the BDS is significantly improved by the polymer viscous rolling process. Finally, the electrostrictive effect was considerably lowered in an optimized BTS-0.1BMT composition. More crucially, a high W-rec of 4.34 J/cm(3) was attained accompanied by excellent temperature stability (variation