Antiferroelectric (AFE) ceramics hold great promise for high energy density capacitors, though their energy storage properties (ESPs) are fundamentally limited by a relatively low breakdown electric field (Eb). Hence, the dual-phase composite ceramics were designed by incorporating a pyrochlore phase into the perovskite matrix to enhance ESPs. Composite ceramics of Y2Zr2O7 modified Pb0.94La0.04Zr0.99Ti0.01O3- x wt% Y2O3 were fabricated and investigated. The introduction of Y2Zr2O7 serves to reduce the overall dielectric permittivity (εr) and enhance insulation, which collectively raise the Eb from 420 kV/cm to 850 kV/cm. A maximum recoverable energy density (Wrec) of 14.5 J/cm3 with an energy efficiency (η) of 85.7% are achieved in the ceramic with x = 4 under 570 kV/cm. In addition, a current density (CD) as high as 2369.4 A/cm2, a power density (PD) of 462 MW/cm3, and an ultrafast discharge rate of 22.6 ns are achieved. This work establishes the construction of dual-phase composites as a viable and novel approach to improving ESPs in PbZrO3 (PZ) -based ceramic systems.