Promising　cotton　fabric　composites　are　designed　to　be　protected　by　flame　retardant　thermoplastic　polyurethane　(TPU)　composites　for　the　next-generation　fire-proof　suit.　Herein,　we　successfully　constructed　flexible　cotton/TPU　hierarchical　composites,　where　a　comfortable　cotton　internal　layer　was　obtained　by　multiple　dip　coating　of　titanium　carbide　(MXene)　and　ammonium　polyphosphate　(APP)/TPU　composites　served　as　external　layers.　The　flame　retardant　and　mechanical　properties　of　its　cotton/TPU　hierarchical　composites　were　tuned　by　adjusting　the　dip　coating　circle.　The　obtained　thermogravimetric　analysis　results　of　the　TPU/APP/Cn　system　indicated　that　the　char　residue　of　MXene-based　cotton/TPU　hierarchical　composites　by　third　dip　coating　increased　from　9.81　to　30.81　wt　%.　Notably,　the　hierarchical　composites　showed　87.2%　and　65%　reductions　in　the　peak　of　heat　release　rate　and　total　heat　release,　respectively,　compared　to　pure　TPU.　Besides,　their　mechanical　performance　was　improved　significantly,　e.g.　the　tensile　strength,　elongation　at　break,　and　toughness　reaching　20　MPa,　400%,　and　30.0　MJ/m3,　respectively.　These　properties　improvements　are　due　to　the　synergistic　effect　between　MXene-based　cotton　and　TPU/APP　composites.　This　work　offers　a　promising　attempt　for　the　design　of　flexible　and　multifunctional　cotton/polymer　hierarchical　composites　with　brilliant　flame　retardancy　and　mechanical　properties.　©　2023　American　Chemical　Society.