This study presents a novel multivalent immune checkpoint therapeutic platform, Nb-Ftn@ICG, constructed by site-specifically ligating an anti-PD-L1 nanobody to the exterior surface of ferritin. The Nb-Ftn nanoplatform effectively targets PD-L1-overexpressing tumor cells, blocks the PD-1/PD-L1 interaction, and downregulates PD-L1 levels through endocytosis-induced degradation. Ferritin's cage structure allows encapsulation of indocyanine green (ICG), an FDA-approved photothermal agent, enabling photothermal therapy (PTT). PTT-induced immunogenic cell death (ICD) in tumor cells enhances systemic immune responses by maturing dendritic cells and increasing T-cell infiltration. In vivo assays demonstrated that Nb-Ftn@ICG ablates primary tumors, suppresses abscopal tumors, and inhibits tumor metastasis, leading to prolonged survival. This work highlights the potential of multivalent nanobody-ferritin conjugates as effective immunological targeting and enhancing carriers in cancer immunotherapy.This study presents a novel multivalent immune checkpoint therapeutic platform, Nb-Ftn@ICG, constructed by site-specifically ligating an anti-PD-L1 nanobody to the exterior surface of ferritin. The Nb-Ftn nanoplatform effectively targets PD-L1-overexpressing tumor cells, blocks the PD-1/PD-L1 interaction, and downregulates PD-L1 levels through endocytosis-induced degradation. Ferritin's cage structure allows encapsulation of indocyanine green (ICG), an FDA-approved photothermal agent, enabling photothermal therapy (PTT). PTT-induced immunogenic cell death (ICD) in tumor cells enhances systemic immune responses by maturing dendritic cells and increasing T-cell infiltration. In vivo assays demonstrated that Nb-Ftn@ICG ablates primary tumors, suppresses abscopal tumors, and inhibits tumor metastasis, leading to prolonged survival. This work highlights the potential of multivalent nanobody-ferritin conjugates as effective immunological targeting and enhancing carriers in cancer immunotherapy.