Endomucin is a type I integral membrane glycoprotein, which is expressed in venous and capillary endothelial cells. It consists of 261 amino acids with an extracellular domain that is highly O‐glycosylated at serine and threonine residues and has several potential N‐glycosylation sites. Endomucin plays an important role in biological processes such as cell interaction, molecular cell signaling, angiogenesis and cell migration, and in recent years it has also been identified as an anti‐adhesion molecule and a marker of endothelial cells. While it has been shown to be involved in a number of physiological and pathological mechanisms, many of its functions remain unknown, and further study is needed. This article reviews research progress on the function of endomucin to date, in order to provide guidance for future studies.