Prostate cancer is an aggressive malignancy with high prevalence and significant mortality, characterized by its remarkable metabolic adaptability and immune complexity. Emerging evidence has highlighted the critical role of post-translational modifications (PTMs) in cancer biology, with protein lactylation gaining attention as a novel PTM with profound implications. Lactylation, derived from lactate, links the altered metabolic processes of tumor cells to diverse cellular functions, including epigenetic regulation and protein dynamics. It significantly influences tumor progression, immune evasion, and therapeutic resistance by modulating key immune cells within the tumor microenvironment. The immunosuppressive conditions created by lactate and lactylation favor tumor survival in prostate cancer. Thus, targeting lactylation offers innovative strategies for treating prostate cancer. By leveraging lactylation modulation, particularly in combination with immune checkpoint inhibitors, there is potential to enhance anti-tumor immune responses and improve treatment outcomes. This review explores the intersection of metabolic alterations and immune modulation, underscoring lactylation as a promising therapeutic avenue in prostate cancer.