Immunogenic ZnP@pyro PDT sensitizes tumors to PD-L1 blockade immunotherapy for the treatment of metastatic tumors. ZnP@pyro PDT induces immunogenic cell death (ICD) and releases tumor-associated antigens, which are presented to naïve T cells to stimulate the production and proliferation of tumor-specific effector T cells. ZnP@pyro PDT also elicits an inflammatory environment to enhance the infiltration of effector T cells and other immune cells, such as B cells and NK cells, into both primary and metastatic tumors. When combined with PD-L1 checkpoint blockade, ZnP@pyro PDT not only eradicates the primary tumors, but also rejects the metastatic tumors by a systemic antitumor immune response.