Here, we describe a convergent synthesis of the human granulocyte-macrophage colony-stimulating factor (hGM-CSF) harboring both O- and N-glycosylation sites using a Se-auxiliary-mediated ligation protocol together with native chemical ligation methodology. The robust and rapid Se-mediated ligation enables assembly of the N-terminus of hGM-CSF in just 4 h, which is significantly faster than the traditional ligation/desulfurization method. Therefore, this new methodology could help to produce hGM-CSF glycoform libraries more efficiently for future elucidation of the importance of glycosylation.