The emerging therapeutic potential of nitric oxide (NO) has spurred the rapid development of NO donors to maximize the therapeutic outcomes. Although polymeric NO donors have shown extended release times and optimized biodistributions, many of these macromolecular NO donors are non-degradable. Herein, we devise a macromolecular NO donor by integrating photoresponsive N,N'-dinitroso-p-phenylenediamine (DNP) derivatives into the middle block of an amphiphilic triblock copolymer and the photo-mediated NO release process transforms the DNP to quinondimine (QDI) moieties, enabling the degradation of the resulting polymers due to the spontaneous hydrolysis of QDI moieties. We demonstrated that the NO release process could be selectively activated under visible light irradiation both in vitro and in vivo. Moreover, the simultaneous release of NO and DOX could be achieved under visible light by taking advantage of the NO release-mediated micelle disassembly. This work provides new insights into the design of degradable macromolecular NO donors where the polymer breakdown could be actuated by triggered NO release.