Polyurethane　(PU)　composites　integrated　with　outstanding　fire　retardancy,　smoke　suppression　as　well　as　ameliorated　mechanical　property　is　attractive,　but　remains　a　challenge.　Here,　we　demonstrate　the　interfacial　architecting　of　organic–inorganic　hybrid　(ACAPP)　by　reacting　renewable　chitooligosaccharide　(COS)　with　ammonium　polyphosphate　(APP)　and　ammonium　octamolybdate　(AOM)　via　a　one-pot,　facile　and　eco-friendly　approach.　The　ACAPP　with　multiple　hydroxyl　groups　shows　good　compatibility　and　strong　interfacial　adhesion　force　with　PU　matrix　due　to　the　abundant　covalent　cross-linking　points　and　hydrogen　bonds　networks.　The　incorporation　of　15　wt%　ACAPP　enables　the　resultant　PU　composite　to　achieve　a　V-0　rating,　a　limiting　oxygen　index　of　26.1%,　31.1%　and　44.8%　reduction　in　total　heat　release　and　total　smoke　production,　respectively,　far　outdistancing　conventional　APP.　The　suppressed　fire　hazards　mainly　benefits　from　the　synergy　catalytic　carbonization　effect　of　ACAPP　in　condensed　phase.　Moreover,　ACAPP　reinforces　the　tensile　strength　of　PU　whilst　retaining　the　decent　ultimate　elongation.　This　work　may　offer　a　referable　exemplification　for　constructing　green　flame-retardant　to　balance　high　fire　safety　and　mechanical　properties.　©　2022　Elsevier　Inc.