Potassium‐ion batteries (PIBs), with the merits of abundant resources and low cost, have rapidly garnered attention as a potential candidate for large‐scale energy storage. Among the various contenders, Prussian blue analogues (PBAs) are considered one of the most suitable cathode materials owing to their relatively easy and economical synthesis as well as the three‐dimensional open framework which facilitates fast potassium ions intercalation without causing drastic volume expansion. Despite these advantages, integrating PBA as a cathode material for PIBs presents substantial challenges, which hinder their further practical applications. Herein, a fundamental review on the development and advance of PBAs in PIBs is presented with the elucidation of their synthesis methods, structural characteristics, and optimization strategies. Particularly, key areas of focus include regulating crystal structures, doping transition metals, engineering interfaces, and employing innovative techniques such as high‐entropy approaches are highlighted. Finally, critical perspectives for future development of PBAs toward practical potassium‐based energy storage devices are proposed.