The　electrode　ionomer　plays　a　crucial　role　in　the　catalyst　layer(CL)of　a　proton-exchange　membrane　fuel　cell(PEMFC)and　is　closely　associated　with　the　proton　conduction　and　gas　transport　properties,structural　stability,and　water　management　capability.In　this　review,we　discuss　the　CL　structural　characteristics　and　highlight　the　latest　advancements　in　ionomer　material　research.Additionally,we　comprehensively　introduce　the　design　concepts　and　exceptional　performances　of　porous　electrode　ionomers,elaborate　on　their　structural　properties　and　functions　within　the　fuel　cell　CL,and　investigate　their　effect　on　the　CL　microstructure　and　performance.Finally,we　present　a　prospective　evaluation　of　the　developments　in　the　elec-trode　ionomer　for　fabricating　CL,offering　valuable　insights　for　designing　and　synthesizing　more　efficient　electrode　ionomer　materials.By　addressing　these　facets,this　review　contributes　to　a　comprehensive　understanding　of　the　role　and　potential　of　electrode　ionomers　for　enhancing　PEMFC　performance.