Artificial　photocatalytic　N2　reduction　to　NH3　under　ambient　conditions　represents　a　promising　alternative　way　for　the　industrial　N2　fixation　by　Haber　−　Bosch　process.　This　work　reports　the　simultaneous　engineering　of　BiOBr　nanosheets　with　exposed　{102}　facets　by　means　of　transition　metal　(Fe,　Mo,　Ni)　doping　and　oxygen　vacancies　(OVs)　that　aid　to　expose　internal　metal　dopants　toward　efficient　visible　light　N2　fixation.　The　synergy　of　transition　metal　doping　and　OVs　results　in　the　modulated　band　structures,　improved　charge　carrier　separation　as　well　as　electron　transfer　to　N2,　thereby　leading　to　enhanced　N2　adsorption　and　activation　ability　over　modified　BiOBr　nanosheets.　In　particular,　the　Fe-doped　BiOBr　with　OVs　possesses　the　optimal　photocatalytic　activity　of　NH3　yield　of　46.1　μmol　g–1　h–1　without　any　sacrificial　agent,　which　is　6-fold　that　of　pristine　BiOBr.　The　findings　will　shed　new　light　on　rational　engineering　of　adsorption,　activation　sites　and　charge　carrier　separation　for　designing　efficient　N2　fixation　photocatalysts.　©　2020　Elsevier　B.V.