A nature-inspired polymer nanoreactor with self-switchable catalytic ability is reported. This nanoreactor was made of platinum nanoparticles and a unique polymer composite of poly(1-vinylimidazole) (PVI) and poly(2-(trifluoromethyl)acrylic acid) (PTFMA) that exhibited “self-healing” properties. This nanoreactor revealed weak reactivity at relatively low temperatures due to the complementary interaction between PVI and PTFMA, which inhibited access to the catalytic sites of platinum. In contrast, the nanoreactor demonstrated significant reactivity at relatively high temperatures, resulting from the dissociation of the interpolymer interaction. Unlike reported nanoreactors which usually involve the thermal phase transition of PNIPAm, this novel nanoreactor has adopted the “self-healing” properties of supramolecular building blocks. The proposed design suggests new opportunities for developing smart nanoreactors capable of self-switchable catalysis.