Nanomedicine enabled cancer combination immunotherapy not only sufficiently activates the host immune system, but also reprograms the immunosuppressive microenvironment, representing a new generation approach to treat cancer. Herein, we demonstrated a targeted photo- and immune-active nanoplatform termed NLG919@HA-Ce6 to simultaneously elicit efficient immunogenic cell death (ICD) using the photosensitizer Ce6 and modulate the tryptophan metabolic pathway using an indoleamine 2,3-dioxygenase (IDO) inhibitor NLG919 for the combined photodynamic therapy (PDT) and checkpoint blockade immunotherapy. Against the triple-negative and poorly immunogenic 4T1 breast cancer model, the stable spherical nanomicelle NLG919@HA-Ce6 selectively killed tumour cells via the toxic singlet oxygen upon laser excitation, thus in situ triggering a potent antitumor immune response, as seen via the obvious CRT exposure, ATP release, dendritic cell maturation, etc. Meanwhile, the IDO1-mediated immunosuppression was effectively reprogrammed to an immunostimulatory phenotype, which was accompanied by an enhanced cytotoxic T cell response as well as reduced Treg infiltration in tumour bed. Ultimately, the 4T1 tumour was synergistically suppressed by NLG919@HA-Ce6 due to the outcome of focused PDT, obvious ICD post PDT and IDO1 blockade. This study suggests the promise of NLG919@HA-Ce6 as an alternative simple, stimulative and targeted nanoagent to enable the whole-body photo-immune therapy against "immune cold" cancer.