Exploiting　cost-effective,　high-efficiency,　and　contamination-free　semiconductors　for　photocatalytic　nitrogen　reduction　reaction　(N2RR)　is　still　a　great　challenge,　especially　in　sacrificial-free　system.　On　basis　of　the　electron　＇acceptance–donation＇　concept,　a　boron-doped　and　carbon-deficient　g-C3N4　(BxCvN) is herein　developed　through　precise　dopant　and　defect　engineering.　The　optimized　B15CvN　exhibisted　an　NH3　production　rate　of　135.3 µmol h−1 g−1　in　pure　water　with　nine-fold　enhancement　to　the　pristine　graphitic　carbon　nitride　(g-C3N4),　on　account　of　the　markedly　elevated　visible-light　harvesting,　N2　activation,　and　multi-directional　photoinduced　carriers　transfer.　The　decorated　B　atoms　with　coexistent　occupied　and　empty　sp3　hybridized　orbitals　are　theoretically　proved　to　be　in　charge　of　the　increase　of　N2　adsorption　energy　from　–0.08　to　–0.26 eV　and　the　change　in　N2　adsorption　model　from　one-way　to　two-way　end-on　pattern.　Noticeably,　the　elaborate　coordination　of　doped　B　atoms　and　carbon　vacancies　greatly　facilitated　the　interlayer　interaction　and　vertical　charge　migration　of　BxCvN,　which is distinctly　revealed　through　the　charge　density　difference　calculations.　The　current　study　provides　an　alternative　groundbreaking　perspective　for　advancing　photocatalytic　N2RR　through　the　targeted　configuration　of　the　defect　and　dopant　sites.　©　2022　Wiley-VCH　GmbH.