Titanium　(Ti)　is　a　promising　biomedical　material　due　to　its　superior　corrosion　resistance,　low　elastic　modulus　and　favorable　biocompatibility.　Nevertheless,　Ti　faces　a　dilemma　because　of　its　inferior　abrasion　performance　and　strength-ductility　trade-off,　which　poses　a　limitation　in　application　as　biomedical　implants.　Here,　we　developed　an　oxygen-charging　method　to　fabricate　a　beta-Ti　alloy　with　combination　of　ultrahigh　surface　hardness,　strength,　toughness　and　remarkable　wear　resistance.　The　superior　mechanical　performance　of　beta-Ti　alloy　originates　from　a　200　mu　m-thick　alpha+beta　phase　hard　shell,　a　600　mu　m　oxygen　gradient　region　and　an　oxygen-free　beta-Ti　core.　The　gradient　phase　and　composition　structures　display　different　deformation　mechanisms,　transforming　from　simple　but　unusual　basal　slip　in　a　phase　to　multiple-slip　activities　in　beta　phase.　The　unique　oxygen　gradient　distribution　makes　beta-Ti　alloy　much　stronger　and　tougher　that　can　resist　surface　crack　propagation　and　sample　catastrophic　failure.　Oxygen　charging　is　a　novel　technique　to　design　high-performance　Ti　implants　for　biomedical　applications.　(C)　2022　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.