Cuproptosis is a new cell death that depends on copper (Cu) ionophores to transport Cu into cancer cells, which induces cell death. However, existing Cu ionophores are small molecules with a short blood half-life making it hard to transport enough Cu into cancer cells. Herein, a reactive oxygen species (ROS)-sensitive polymer (PHPM) is designed, which is used to co-encapsulate elesclomol (ES) and Cu to form nanoparticles (NP@ESCu). After entering cancer cells, ES and Cu, triggered by excessive intracellular ROS, are readily released. ES and Cu work in a concerted way to not only kill cancer cells by cuproptosis, but also induce immune responses. In vitro, the ability of NP@ESCu to efficiently transport Cu and induce cuproptosis is investigated. In addition, the change in the transcriptomes of cancer cells treated with NP@ESCu is explored by RNA-Seq. In vivo, NP@ESCu is found to induce cuproptosis in the mice model with subcutaneous bladder cancer, reprograming the tumor microenvironment. Additionally, NP@ESCu is further combined with anti-programmed cell death protein ligand-1 antibody (αPD-L1). This study provides the first report of combining nanomedicine that can induce cuproptosis with αPD-L1 for enhanced cancer therapy, thereby providing a novel strategy for future cancer therapy.