This review provides a synthesis of the current understanding of lactate and lactylation in tumor immunosuppression, detailing molecular mechanisms underlying immune cell inhibition (tumor-associated macrophages, T cells, T-reg cells, NK cells and NKT cells, as well as neutrophils) and evaluating emerging therapeutic strategies (e.g., inhibitors of MCTs/LDHA, site-specific antibodies, genetic code expansion technology). Here, LDHA is linked to neoplasm.