<p>Lactylation is a recently identified metabolism-associated post-translational modification that provides a mechanistic link between tumor metabolic reprogramming and epigenetic regulation. Although aberrant lactate accumulation in tumor tissues has long been recognized, a comprehensive and unified understanding of how lactate-derived modifications contribute to tumor initiation and progression remains lacking. Here, we use lactate metabolism as a conceptual framework to systematically review the biogenesis and regulatory networks of lactylation, with a particular focus on its functions and underlying molecular mechanisms in key malignant processes, including tumor proliferation, invasion and metastasis, angiogenesis, immune evasion, radiotherapy resistance and systemic therapy resistance. Furthermore, we review emerging anti-tumor therapeutic strategies targeting lactate metabolism and tumor lactylation, highlighting that glucose metabolism–driven lactate accumulation and lactylation play a pivotal role in sustaining tumor cell survival and immunosuppressive phenotypes. Inhibition of lactate metabolism markedly attenuates tumor-associated lactylation and exhibits substantial synergistic efficacy when combined with other anti-tumor therapies. Overall, this work advances a systematic understanding of the roles of lactylation in tumor malignant progression and provides an important conceptual and theoretical foundation for the development of novel cancer therapeutic strategies targeting protein lactylation.</p>