This chapter explores the potential of perovskite-based ferroelectric, relaxor, and antiferroelectric materials for high-performance capacitive energy storage. It emphasizes the unique dielectric properties of relaxor ferroelectrics, which exhibit high energy densities due to their low remnant polarization and slim hysteresis loops. Lead-based systems like PZT offer high performance but raise environmental concerns, prompting a shift toward lead-free alternatives. The chapter reviews synthesis methods, structural characteristics, and energy storage performance of both lead-containing and lead-free perovskites such as BNT, BT, NN, BMN, and ATN. Techniques like doping, microstructure engineering, and multilayer design are discussed as means to enhance energy density and efficiency. The role of polar nanoregions (PNRs) and phase transitions in optimizing dielectric response is highlighted. Challenges such as improving breakdown strength, thermal/frequency stability, and reducing leakage currents are analysed. The chapter also outlines promising applications, including actuators, sensors, and biomedical devices. Future directions involve high-entropy designs, advanced characterization methods, and integration of computational modelling. Overall, perovskite relaxors are shown to be highly promising for next-generation energy storage systems.