Dielectric materials with high dielectric constant and breakdown voltage are very promising for pulsed energy storage applications. In this paper, (1-x) BaTiO3-xBiYO3 (x=0–0.5) ceramics were synthesized using conventional solid-state reaction method. The ceramic structure transformed from ferroelectric tetragonal phases (x≤0.5) to pseudo-cubic phases (x≥0.1). When x=0.2, beyond the solid solubility limit of BaTiO3-BiYO3, the second phase and glassy phases were formed, accompanying lattice parameter excursion. It revealed a gradual change from classic ferroelectric behavior in pure BaTiO3 to highly diffusive and dispersive relaxor-like characteristics with BiYO3 content increasing. It exhibited high polarization maximum and low remnant polarization, which was favorable for energy storage in (1-x)BaTiO3-xBiYO3 ceramics, due to the disrupted long polarization, the created weak coupling and the formed second phase. Furthermore, the nonlinearity of the (1-x)BaTiO3-xBiYO3 ceramics were weakened obviously. A maximum energy storage density of 0.316J/cm3 at 66kV/cm with relative high energy efficiency of 82.7% was achieved in 0.8BaTiO3-0.2BiYO3 ceramic, which indicated that (1-x)BaTiO3-xBiYO3 ceramics were promising lead-free relaxor materials for energy storage applications.