We present a novel approach to the synthesis of polymeric nanocomposites in which noble metal nanoparticles (NP) are covalently bonded to a polymer matrix. In this approach, the NPs are functionalized with novel aminothioalkil ligands that are capable to bind chemically to a wide range of polymers possessing carbonyl groups or hydroxyl groups that can be oxidized into carbonyl groups. This method is illustrated by the ex situ incorporation of gold, platinum, and silver NPs decorated with the aminothioalkil ligands into matrices of natural polymers such as potato starch, cellulose, as well as synthetic polymers – poly(vinyl)alcohol, carboxymethylcellulose, and copolymer of maleic anhydride and styrene. It is demonstrated that in the obtained nanocomposites the functionalized NPs are covalently linked to the polymer matrix via amide, imide, imine, or aminal bonds. We show that the binding reaction of the aminothioalkil ligands with the polymer chains occurs spontaneously at room temperature only when the aminothioalkil ligands are attached to the surface of the NPs.