IL‐2 is a known potent T cell growth factor that amplifies lymphocyte responses in vivo. This capacity has led to the use of high‐dose IL‐2 to enhance T cell immunity in patients with AIDS or cancer. However, more recent studies have indicated that IL‐2 is also critical for the development and peripheral expansion of regulatory T cells (Tregs). In the current study, low‐dose IL‐2 (1 million IU/m2 BSA/day) was administered to expand Tregs in vivo in naïve nonhuman primates. Our study demonstrated that low‐dose IL‐2 therapy significantly expanded peripheral blood CD4+ and CD8+ Tregs in vivo with limited expansion of non‐Treg cells. These expanded Tregs are mainly CD45RA− Foxp3 high activated Tregs and demonstrated potent immunosuppressive function in vitro. The results of this preclinical study can serve as a basis to develop Treg immunotherapy, which has significant therapeutic potential in organ/cellular transplantation.