Abstract: In recent years, numerous studies have elucidated the correlation between DNA methylation and gastric cancer (GC) from the perspectives of early diagnosis, targeted therapy, and prognosis assessment. However, the clinical understanding of their relationship remains incomplete and insufficiently explored. This review will summarize the research progress on the role of DNA methylation in GC, focusing on methylation markers currently approved for GC detection, DNA methylation-based diagnostic markers utilizing liquid biopsy techniques, as well as the relationship between DNA methylation and GC treatment and prognosis. The aim is to provide further insights for the clinical diagnosis and treatment of GC.