The　local　coordination　structure　of　metal　sites　essentially　determines　the　performance　of　supported　metal　catalysts.　Using　a　surface　defect　enrichment　strategy,　we　successfully　fabricated　Pt　atomic　single-layer　(PtASL)　structures　with　100%　metal　dispersion　and　precisely　controlled　local　coordination　environment　(embedded　vs　adsorbed)　derived　from　Pt　single-atoms　(Pt-1)　on　ceria-alumina　supports.　The　local　coordination　environment　of　Pt-1　not　only　governs　its　catalytic　activity　but　also　determines　the　Pt-1　structure　evolution　upon　reduction　activation.　For　CO　oxidation,　the　highest　turnover　frequency　can　be　achieved　on　the　embedded　PtASL　in　the　CeO2　lattice,　which　is　3.5　times　of　that　on　the　adsorbed　PtASL　on　the　CeO2　surface　and　10-70　times　of　that　on　Pt-1.　The　favorable　CO　adsorption　on　embedded　PtASL　and　improved　activation/reactivity　of　lattice　oxygen　within　CeO2　effectively　facilitate　the　CO　oxidation.　This　work　provides　new　insights　for　the　precise　control　of　the　local　coordination　structure　of　active　metal　sites　for　achieving　100%　atomic　utilization　efficiency　and　optimal　intrinsic　catalytic　activity　for　targeted　reactions　simultaneously.