A novel multivalent anti-PD-L1 nanobody-ferritin (Nb-Ftn) nanoplatform was developed to enhance cancer immunotherapy. This platform combines the tumor-targeting ability of anti-PD-L1 nanobodies with the structural stability and cargo-carrying capacity of ferritin nanocages. The Nb-Ftn nanoplatform was designed to block the PD-1/PD-L1 interaction, downregulate PD-L1 levels via lysosomal degradation, and deliver photothermal therapy (PTT) using indocyanine green (ICG) encapsulated within the ferritin cage. The Nb-Ftn@ICG nanoplatform demonstrated enhanced tumor targeting, cellular uptake, and retention of ICG, leading to effective photothermal treatment and immunogenic cell death (ICD) of tumor cells. This process promotes dendritic cell maturation, T-cell infiltration, and immune checkpoint blockade, resulting in improved antitumor efficacy. In vivo studies showed that Nb-Ftn@ICG significantly ablated primary tumors, suppressed abscopal tumors, and inhibited metastasis, leading to prolonged survival in mice. The Nb-Ftn nanoplatform also exhibited strong photothermal effects, with increased temperature elevation and reactive oxygen species (ROS) generation compared to free ICG. The multivalent nature of Nb-Ftn enhanced its binding affinity, stability, and in vivo circulation, making it a promising candidate for cancer immunotherapy. This study highlights the potential of nanobody-ferritin conjugates as a novel strategy for improving immunotherapy through enhanced targeting, immune checkpoint inhibition, and photothermal treatment.A novel multivalent anti-PD-L1 nanobody-ferritin (Nb-Ftn) nanoplatform was developed to enhance cancer immunotherapy. This platform combines the tumor-targeting ability of anti-PD-L1 nanobodies with the structural stability and cargo-carrying capacity of ferritin nanocages. The Nb-Ftn nanoplatform was designed to block the PD-1/PD-L1 interaction, downregulate PD-L1 levels via lysosomal degradation, and deliver photothermal therapy (PTT) using indocyanine green (ICG) encapsulated within the ferritin cage. The Nb-Ftn@ICG nanoplatform demonstrated enhanced tumor targeting, cellular uptake, and retention of ICG, leading to effective photothermal treatment and immunogenic cell death (ICD) of tumor cells. This process promotes dendritic cell maturation, T-cell infiltration, and immune checkpoint blockade, resulting in improved antitumor efficacy. In vivo studies showed that Nb-Ftn@ICG significantly ablated primary tumors, suppressed abscopal tumors, and inhibited metastasis, leading to prolonged survival in mice. The Nb-Ftn nanoplatform also exhibited strong photothermal effects, with increased temperature elevation and reactive oxygen species (ROS) generation compared to free ICG. The multivalent nature of Nb-Ftn enhanced its binding affinity, stability, and in vivo circulation, making it a promising candidate for cancer immunotherapy. This study highlights the potential of nanobody-ferritin conjugates as a novel strategy for improving immunotherapy through enhanced targeting, immune checkpoint inhibition, and photothermal treatment.