Hepatocellular carcinoma (HCC) is a common malignant tumor. Histone lactylation, a novel epigenetic modification, plays a crucial role in various cancers. However, the functional role and underlying mechanism of histone lactylation in HCC progression have not yet been investigated. Histone lactylation levels in HCC tissues and cells were assessed using a densitometric kit and western blot analysis. The role of histone lactylation in cell malignant phenotypes was determined through functional assays in vitro, and a xenograft tumor model was established to verify the function of histone lactylation in vivo. ChIP assay was performed to explore the interaction between histone lactylation and endothelial cell-specific molecule 1 (ESM1). Additionally, gain-and-loss-of-function assays were conducted to investigate the regulatory role of ESM1 in HCC pathogenesis. Histone lactylation levels were increased in HCC tissues and cells, and H3K9 lactylation (H3K9la) and H3K56 lactylation (H3K56la) were identified as the histone modification sites. We observed that H3K9la and H3K56la caused abnormal histone lactylation and were associated with poor prognosis. Functionally, histone lactylation was found to promote HCC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) process in vitro. However, histone lactylation inhibition with 2-deoxy-d-glucose (2-DG) reduced the malignant phenotypes of HCC cells. In vivo, 2-DG treatment reduced tumor growth and metastasis in the HCC mouse model. Mechanistically, it was revealed that histone lactylation activated ESM1 transcription in HCC cells. ESM1 was expressed at a high level in HCC and exerted a carcinogenic role. Histone lactylation facilitates cell malignant phenotypes, tumor growth, and metastasis by upregulating ESM1 expression in HCC, which reveals the downstream molecular mechanism of histone lactylation and might provide a novel therapeutic target for HCC therapy.