Ultrathin　TiO2　nanosheets　(NST)　containing　Ti3+　sites　are　developed　as　a　photocatalyst　that　exhibits　high　degradation　efficiencies　(98.6%)　for　the　degradation　of　enrofloxacin　(ENR)　under　visible　light.　The　increment　of　degradation　efficiencies　for　ENR　over　NST　is　mainly　due　to　the　increase　of　Ti3+　and　oxygen　vacancies　(OVs).　Ti3+　sites　on　the　surface　of　NST　can　be　associated　with　ENR　molecules　through　the　formation　of　surface　coordination　species　-COOTi-　intermediates,　resulting　in　the　activation　of　ENR.　OVs　on　NST　can　adsorb　and　activate　more　O2　molecules　to　accelerate　the　generation　of　O2-　by　photogenerated　electrons　reduction.　The　photogenerated　holes　quickly　transfer　to　the　surface　of　the　catalyst　to　directly　degrade　the　activated　ENR.　Finally,　a　possible　mechanism　about　the　synergistic　effect　of　coordination　activation　and　photocatalysis　is　proposed　over　NST　at　a　molecule　level.　This　study　highlights　the　significant　role　of　coordination　activation　in　the　photocatalytic　degradation　of　antibiotics.　©　2023　Elsevier　B.V.