Light-responsive polymers are of great interest today due to their various applications, especially in the field of drug delivery. In this work, poly(amidoamine) dendrimer with ethylenediamine core up to the fourth generation has been synthesized. Then, the terminal amine groups of the dendrimer have been conjugated to different amounts of 7-(carboxymethoxy)-4-methylcoumarin. 7-(Carboxymethoxy)-4-methylcoumarin has been synthesized by the reaction between 4-methylumbelliferone and ethyl bromoacetate. The synthesis of different structures has been confirmed using FTIR and 1H NMR spectroscopies. Also, the fluorescence properties of dendrimer-coumarin nanoparticles have been investigated by fluorescence microscopy. Synthesized hybrids have been exposed to self-assembly process and then crosslinked under UV light irradiation. Spherical morphology was observed for self-assembled specimens before and after crosslinking in nanometer dimensions by FE-SEM. The crosslinked samples had smaller particle sizes than the non-crosslinked samples, and the particle size was increased with increasing coumarin moieties. Moreover, dendrimer-coumarin samples were assembled in aqueous solution after crosslinking and morphologies were studied by FE-SEM images. The synthesized supramolecular structures before and after crosslinking were used as nanocarriers of DOX and release behavior was investigated at pH = 1 and 7.4 and under 254 nm-UV-light irradiation. Results showed that low pH value and irradiation of UV light resulted in more cumulative drug release.