The light-induced formation of pH and temperature-responsive poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) nanocages is demonstrated here. The strategy is based on the self-assembly in aqueous solutions of a photocleavable poly(tert-butyl acrylate)-hv-poly[2(dimethylamino)ethyl methacrylate] block copolymer (PtBA-hv-PDMAEMA, where -hv- is the photocleavable junction) into spherical micelles, followed by first PDMAEMA cross-linking by a bis-iodo compound and then by UV light irradiation. The exposure to light induces the cleavage of the junction between the PtBA core and the cross-linked PDMAEMA shell of the micelles. The PtBA block is then extracted to obtain the desired nanocages. The size change of the nanocages in response to pH and temperature is investigated by dynamic light scattering. Finally, the ability to functionalize the internal cavity of the nanocages is demonstrated.