α-Zirconium phosphate nanoplatelets have been alternatively combined with a cationic polyelectrolyte (polydiallyldimethylammonium chloride), a polyhedral oligomeric silsesquioxane or with alumina-coated silica nanoparticles, exploiting the layer-by-layer deposition. The obtained nanostructured assemblies have been applied to polyester, poly(ethyleneterephthalate), fabrics in order to enhance their thermal and fire stability, with particular attention to the reduction of smokes and toxic gases (carbon monoxide produced during the combustion). The treated fabrics evidenced a significant improvement of their thermal and thermo-oxidative stability, together with an increased time to ignition (86%), a lowering of heat release rate (26%), as well as a significant decrease in smoke release rate (25%) and production of carbon monoxide (35%). Thus, the proposed approach may turn out to be very advantageous for conferring flame retardancy to textiles.