<p>Ionic covalent organic frameworks (ICOFs), as an emerging subclass of covalent organic frameworks (COFs), have garnered significant attention owing to their unique integration of structural precision and ionic functionality. Although conventional neutral COFs possess excellent crystallinity, tunable porosity, and high stability, their limited electronic tunability and poor charge-transport properties have constrained their performance in various applications. The incorporation of ionic sites into COF skeletons or pore environments effectively overcomes these intrinsic limitations. The presence of charged centres enhances framework polarity, modulates local electrostatic fields, and facilitates efficient ion migration and charge separation, thereby endowing ICOFs with superior functionality. As a result, ICOFs have demonstrated remarkable potential in diverse fields, including adsorption, sensing, ion conduction, energy devices, photocatalysis, and electrocatalysis. This review provides an integrative perspective by systematically linking framework design, ionic site engineering, structure-property relationships, and functional performance in various applications, highlighting ICOFs distinct advantages over neutral COFs and providing fundamental insights for the rational design of next-generation ionic frameworks toward energy and environmental applications.</p>