Aqueous　zinc–iodine　(Zn–I2)　batteries　have　attracted　considerable　research　interest　as　an　alternative　energy　storage　system　due　to　their　high　specific　capacity,　intrinsic　safety,　and　low　cost.　However,　the　notorious　shuttle　effect　of　soluble　polyiodides　causes　severe　capacity　loss　and　poor　electrochemical　reversibility,　restricting　their　practical　usage.　Herein,　this　study　reports　a　bifunctional　binder　(polyacrylonitrile　copolymer,　as　known　as　LA133)　with　strong　iodine-chemisorption　capability　for　aqueous　Zn–I2　batteries　to　suppress　polyiodide　shuttling.　From　both　calculation　and　experimental　data,　this　study　reveals　that　the　amide　and　carboxyl　groups　in　LA133　binder　can　strongly　bond　to　polyiodides,　significantly　immobilizing　them　at　cathode　side.　As　a　result,　fewer　byproducts,　slower　hydrogen　evolution,　and　lesser　Zn　dendrite　in　the　Zn–I2　battery　are　observed.　Consequently,　the　battery　shows　high　specific　capacity　(202.8 mAh g−1)　with　high　iodine　utilization　efficiency　(96.1%),　and　long　cycling　lifespan　(2700　cycles).　At　the　high　mass　loading　of　7.82 mg cm−2,　the　battery　can　still　retain　83.3%　of　its　initial　capacity　after　1000　cycles.　The　specific　capacity　based　on total　cathode　slurry　mass　reaches　71.2 mAh g−1,　higher　than　most　of　the　recent　works.　The　strategy　opens　a　new　avenue　to　address　the　shuttling　challenge　of　Zn–I2　batteries　through　bifunctional　binder.　©　2024　The　Authors.　Advanced　Energy　Materials　published　by　Wiley-VCH　GmbH.