To address the global challenges associated with energy and environmental concerns, the design, development, and application of novel materials have emerged as pivotal drivers. Notably, high-entropy perovskite oxides (HEPOs) amalgamate the merits of both perovskite oxides and high-entropy materials, presenting significant potential in addressing numerous critical issues in energy and environment. This review delves into the recent advancements of HEPOs in these domains. Firstly, it provides an overview of prevalent synthesis techniques for HEPOs, alongside two emerging low-temperature, eco-friendly methods. Subsequently, current strategies to optimize the performance of HEPOs are summarized from three perspectives: compositional engineering, morphological engineering, and structural engineering. The review further underscores their applications in areas such as lithium-ion batteries, supercapacitors, electrocatalysts, and solid oxide fuel cells. Based on this foundation, potential performance optimization strategies and potential application areas of HEPOs are discussed. Finally, it identifies challenges faced by further development of HEPOs in energy and environmental applications and provides an outlook on future developments.