Under the burgeoning call towards miniaturization and environmental-friendliness, it is of paramount importance in developing lead-free dielectrics for energy storage applications. However, obstacles stand out concerning to the incomprehensive energy storage properties of the lead-free dielectric ceramics. Here, a synergistic optimization strategy is proposed involving the Sr0.7Bi0.2TiO3 (SBT) modified Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT), where the as-obtained (1-x)BCZT-xSBT ceramics exhibit an excellent recoverable energy storage density (4.02 J/cm3) with high energy storage efficiency (93.49%) at high electric field of 480 kV/cm. Meanwhile, ultra-fast discharge time (t0.9) of 103 ns and high power density (PD) of 237.83 MW/cm3 have been concurrently realized. Temperature-dependent Raman spectroscopy and piezo-response force microscopy (PFM) are conducted to reveal the mechanisms for the superior properties achieved, which ascertain the quick reversibility of domains and relaxor ferroelectric behaviors in the (1-x)BCZT-xSBT ceramics. This work underpins the significance of synergistic optimization in enhancing the energy storage properties for lead-free dielectrics and promoting their applications in energy storage devices.