In this chapter, the authors address the main properties derived from the multifunctionality of the nanocomposites and presents potential applications in the fields of catalysis and sensing. They focuses on hybrid nanocomposites consisting of a single metal nanoparticle core and a thermoresponsive polymer shell. The authors restrict themselves to shells made of poly-N-isopropylacrylamide (pNIPAM), since this is the standard microgel model system and it has been used in most of the work related to this particular type of nanocomposites. They provide an overview of the different synthetic approaches, with an emphasis on the effect of the obtained structure on the main properties that are characteristic of these materials. The authors also address different applications, as well as future perspectives. An initial protocol was developed that involved the polymerization of styrene and divinylbenzene at the surface of the metal particles prior to introducing them in the pNIPAM polymerization medium.