Regulatory T (Treg) cells are indispensable for peripheral tolerance and immune homeostasis. Protein glycosylation plays an essential role in various cellular functions of T cells, including T cell development, thymocyte selection, T cell activation and differentiation. Recently, many studies have explored the effects of glycosylation on Treg biology. Both N-linked glycosylation and O-linked glycosylation are important for the development, migration, suppressive function and lineage stability of Treg cells. In this review, we will discuss emerging evidence of glycosylation regulations on Treg cells and the developing technologies on the detection and analysis of unique glycan patterns and branching features. These efforts will help to reveal the function and regulatory roles of glycan remodeling in Treg cells, explore how glycan patterns modulate their phenotypes, and provide a strategic basis for clinical intervention and therapy of inflammatory diseases by targeting key glycosylation molecules in Treg cells.