Construction of multifunctional nanoplatforms to elevate chemotherapeutic efficacy and induce long-term antitumor immunity still remains to be an extreme challenge. Herein, we report the design of an advanced redox-responsive nanomedicine formulation based on phosphorus dendrimer-copper(II) complexes (1G3-Cu)- and toyocamycin (Toy)-loaded polymeric nanoparticles (GCT NPs) coated with cancer cell membranes (CM). The designed GCT@CM NPs with a size of 210 nm are stable under a physiological condition but are rapidly dissociated in the reductive tumor microenvironment to deplete glutathione and release drugs. The co-loading of 1G3-Cu and Toy within the NPs causes significant tumor cell apoptosis and immunogenic cell death through 1G3-Cu-induced mitochondrial dysfunction and Toy-mediated amplification of endoplasmic reticulum stress, respectively, thus effectively suppressing tumor growth, promoting dendritic cell maturation, and increasing tumor-infiltrating cytotoxic T lymphocytes. Likewise, the coated CM and the loaded 1G3-Cu render the GCT@CM NPs with homotypic targeting and T1-weighted magnetic resonance imaging of tumors, respectively. With the assistance of programmed cell death ligand 1 antibody, the GCT@CM NP-mediated chemotherapy can significantly potentiate tumor immunotherapy for effective inhibition of tumor recurrence and metastasis. The developed GCT@CM NPs hold a great potential for chemotherapy-potentiated immunotherapy of different tumor types through different mechanisms or synergies.