Critical-sized　bone　defects　caused　by　trauma,　congenital　malformation,　or　tumor　resection　remain　a　major　challenge　around　the　world.　Current　bone　tissue-engineering　scaffolds　are　partially　confined　by　inadequate　scaffold　architecture　design　that　mismatches　with　natural　bone　tissue,　which　affect　normal　biological　functions　like　inflammation　modulation　and　biomineralization,　thus　impairing　bone　regeneration　process.　Herein,　a　biomimetic　3D-printed　BMGP　scaffold　composed　of　polydopamine　(PDA)-polylactide　(PLA)　scaffold　and　black　phosphorus　(BP)　nanosheets/manganese　carbonyl　(MnCO)　nanosheets/gelatin　methacryloyl　hydrogel　(named　as　BMG　hydrogel)　was　developed　for　augmenting　bone　regeneration　via　strengthening　anti-inflammatory　effect　and　promoting　in-situ　biomineralization　process.　Through　infilling　the　BMG　hydrogel　into　the　gradient-porous　PDA-PLA　scaffold,　the　obtained　BMGP　scaffold　successfully　mimicked　cancellous　and　compact　bone　structure　and　extracellular　matrix　component　in　natural　bone　tissue.　Upon　being　implanted　into　the　critical-sized　bone　defect,　a　Fenton-like　reaction　between　the　MnCO　nanosheet　and　endogenous　hydrogen　peroxide　effectively　induced　carbon　monoxide　release,　thereby　improving　anti-inflammatory　response　and　facilitating　macrophage　reversed　from　pro-inflammatory　M1　phenotype　to　anti-inflammatory　M2　phenotype.　Meanwhile,　the　BP　nanosheet　underwent　degradation　and　in-situ　biomineralization,　which　accelerated　calcium　phosphate　formation　and　enhanced　osteogenesis.　Based　on　in-vitro　and　in-vivo　data,　the　3D-printed　BMGP　scaffold　that　integrated　structural　and　functional　biomimicry　exhibited　desirable　inflammatory　inhibition　and　in-situ　biomineralization　performances,　as　well　as　favorable　osteogenic　effect　in　rat　critical-sized　femoral　bone　defect.　In　all,　such　biomimetic　scaffold　obviously　propelled　bone　regeneration　process,　and　provided　a　promising　strategy　for　treating　critical-sized　bone　defects　in　clinic.　©　2025　Elsevier　B.V.