Post‑translational modifications (PTMs) of proteins influence their functionality by altering the structure of precursor proteins. These modifications are closely linked to tumor progression through the regulation of processes such as cell proliferation, apoptosis, angiogenesis and invasion. Tumors produce large amounts of lactic acid through aerobic glycolysis. Lactic acid not only serves an important role in cell metabolism, but also serves an important role in cell communication. Lactylation, a PTM involving lactate and lysine residues as substrates, serves as an epigenetic regulator that modulates intracellular signaling, gene expression and protein function, thereby serving a crucial role in tumorigenesis and progression. The identification of lactylation provides a key breakthrough in elucidating the interaction between tumor metabolic reprogramming and epigenetic modification. The present review primarily summarizes the occurrence of lactylation, its effect on tumor progression, drug resistance, the tumor microenvironment and gut microbiota, and its potential as a therapeutic target for cancer. The aim of the present review was to provide novel strategies for potential cancer therapies.