Environmental stimuli-responsive nucleobase-functionalized supramolecular polymers, a combination of oligomeric polypropylene glycol segments as a thermosensitive element and hydrogen-bonded uracil as a photosensitive moiety, were successfully developed and undergo spontaneous self-assembly to form uniform nanosized micelles via self-complementary double hydrogen bonding interactions between the uracil moieties in an aqueous environment. These micelles exhibit unique properties such as dual thermo- and photoresponsiveness, controllable lower critical concentration solution temperature (LCST), photoreactivity, and morphological transformation, making them highly attractive for various applications. More importantly, phase transitions and morphological studies confirmed the LCST behavior, size, and shape of the micelles can be easily tuned by adjusting the concentration and duration of ultraviolet irradiation of samples in aqueous solution, indicating introduction of uracil molecules into a water-soluble polymer matrix may represent a promising approach toward development of multiple stimuli responsive polymeric micelles whose self-assembly behavior can be manipulated. In view of the ease of fabrication, high biocompatibility, multifunctionality, and tailorable micellar properties, this newly developed supramolecular micelle may be a promising candidate nanocarrier for controlled drug delivery and bioimaging systems.