Photodynamic therapy (PDT) has gained significant attention for its potential to modulate the immune system in cancer treatment. Recent studies have shown that PDT can influence both the innate and adaptive arms of the immune response, leading to the recruitment and activation of immune cells such as neutrophils, macrophages, and dendritic cells. Clinical trials are underway to evaluate the effectiveness of PDT in treating various types of cancer and its impact on the immune system. Notably, PDT has been found to enhance immune responses by increasing the expression of adhesion molecules, complement system activation, and the production of inflammatory cytokines. Additionally, combination approaches involving PDT and immunotherapy have shown promising results in clinical trials. Despite these advancements, further research is needed to fully understand the mechanisms underlying the immune activation by PDT. This review aims to comprehensively summarize and discuss ongoing and completed studies that evaluate the impact of PDT on the immune response in cancer treatment.Photodynamic therapy (PDT) has gained significant attention for its potential to modulate the immune system in cancer treatment. Recent studies have shown that PDT can influence both the innate and adaptive arms of the immune response, leading to the recruitment and activation of immune cells such as neutrophils, macrophages, and dendritic cells. Clinical trials are underway to evaluate the effectiveness of PDT in treating various types of cancer and its impact on the immune system. Notably, PDT has been found to enhance immune responses by increasing the expression of adhesion molecules, complement system activation, and the production of inflammatory cytokines. Additionally, combination approaches involving PDT and immunotherapy have shown promising results in clinical trials. Despite these advancements, further research is needed to fully understand the mechanisms underlying the immune activation by PDT. This review aims to comprehensively summarize and discuss ongoing and completed studies that evaluate the impact of PDT on the immune response in cancer treatment.