The anisotropic emission properties of an Eu(III)-MWCNTs-based nano-composite PNIPAAm hydrogel is induced upon application of a 10 T magnetic field, the latter dictating the alignment of the carbon nanotubes. This structuration creates directional highways for light to be preferentially absorbed, giving rise to orientation-dependent light emission intensity. Thermal control of the transparency of the aqueous matrix also allowed a stimulus-induced switching of the materials' emission properties.