Tofacitinib is an oral synthetic small-molecule inhibitor of Janus kinases, which are involved in the pathogenesis of various inflammatory diseases, representing a new therapeutic option for ulcerative colitis. The efficacy and safety of tofacitinib have been demonstrated in clinical trials in patients with moderate to severe ulcerative colitis, and it has recently been approved by the European Medicines Agency to treat this disease. This article reviews the most relevant characteristics of tofacitinib, its main differences from biological agents, the studies which demonstrate its efficacy in patients with ulcerative colitis, and its optimal use in different clinical situations.