A　visible-light-induced　synergistic　hydrogen　atom　transfer　(HAT)　and　proton　transfer　(PT)　catalysis　was　developed　for　the　defluorinative　carboxylation　of　α-CF2R-substituted　alkenes.　This　system　affords　a　variety　of　γ,γ-difluoro-　and　γ-monofluorovinylacetic　acids　without　stepwise　acidification,　exhibiting　good　functional　group　tolerance,　broad　scope,　and　facile　scalability.　Mechanism　studies　support　that　thiol　plays　the　role　of　the　hydrogen　relay,　which　s　a　hydrogen　atom　through　HAT　and　then　outputs　a　proton　via　PT.　This　strategy　also　takes　full　advantage　of　formate　for　photocatalytic　carboxylation　reaction　in　a　step-　and　atom-economical　way.　©　Science　China　Press　2025.