Chlorination,　one　of　the　most　common　oxidation　strategies,　performed　limited　degradation　capacity　towards　many　emerging　organic　contaminants　under　neutral　pH　conditions.　In　this　study,　2,2′-azinobis(3-ethylbenzothiazoline)-6-sulfonate　(ABTS)　was　discovered　to　possess　an　outstanding　activation　property　towards　free　available　chlorine　(FAC)　during　the　chlorination　of　diclofenac　(DCF)　among　pH　6.0–9.5.　ABTS　radical　(ABTS•+)　primarily　accounted　for　the　elimination　of　DCF　in　the　ABTS/FAC　system,　although　hydroxyl　radicals,　reactive　chlorine　species,　and　singlet　oxygen　were　also　generated　via　the　self-decomposition　of　FAC.　ABTS　acted　as　the　electron　shuttle　to　degrade　DCF　in　the　ABTS/FAC　system,　where　ABTS　was　firstly　oxidized　by　FAC　to　ABTS•+　via　single　electron　transfer,　and　followed　by　the　elimination　of　DCF　with　the　generated　ABTS•+.　Eight　DCF　degradation　intermediates　were　identified　by　LC/Q-TOF/MS,　and　four　DCF　degradation　pathways　were　proposed.　Real　water　bodies,　humic　acid,　and　the　coexistent　anions　of　Cl−,　HCO3−,　NO3−,　and　SO42−　performed　negligible　influence　on　DCF　removal　in　ABTS/FAC　system.　ABTS/FAC　system　was　much　superior　to　sole　chlorination　in　terms　of　toxicity　reduction　and　anti-interference　capacity.　Overall,　this　study　innovatively　introduced　ABTS　as　the　electron　shuttle　to　enhance　the　oxidative　capacity　of　FAC　under　neutral　pH　conditions　and　provided　a　new　insight　that　the　ABTS-like　organic/synthetic　components　might　play　an　important　role　in　degrading　emerging　organic　contaminants　by　chlorination　in　water　treatment.　©　2023　Elsevier　B.V.