In this study, a simple one-pot method was used to prepare a multifunctional platform for synergistic chemo- and photothermal therapy,, which is composed of zeolitic imidazolate framework-8 (ZIF-8) as drug nanocarriers and the embedded graphene quantum dots (GQDs) as local photothermal seeds. The structure, drug release behavior, photothermal effect, and synergistic therapeutic efficiency of the ZIF-8/GQD nanoparticles were systematically investigated. Using doxorubicin (DOX) as a model anticancer drug, the results showed that monodisperse ZIF-8/GQD nanoparticles with a particle size of 50–100 nm could encapsulate DOX during the synthesis procedure and trigger DOX release under acidic conditions. The DOX-loaded ZIF-8/GQD nanoparticles could efficiently convert near-infrared (NIR) irradiation into heat and thereby increase the temperature. More importantly, with breast cancer 4T1 cells as a model cellular system, the results indicated that the combined chemo- and photothermal therapy with DOX-ZIF-8/GQD nanoparticles exhibited a significant synergistic effect, resulting in a higher efficacy to kill cancer cells compared with chemotherapy and photothermal therapy alone. Hence, ZIF-8/GQD nanoparticles would be promising as versatile nanocarriers for synergistic cancer therapy.