Psoriatic arthritis (PsA) and ulcerative colitis (UC) are immune-mediated diseases that cause significant burden worldwide. Recent advances in their management have improved patient outcomes. However, significant unmet needs still remain as not all patients respond to current treatments, and patients may lose responsiveness over time. An improved understanding of the pathophysiology of these diseases has brought about the development of novel disease-modifying agents, including interleukin inhibitors and, more recently, Janus kinase (JAK) inhibitors. With the approval of tofacitinib for the treatment of adults with active PsA and in adult patients with moderately-to-severely active UC, JAK inhibitors have recently entered the treatment armamentarium for PsA and UC. A number of other JAK inhibitors are also undergoing clinical development and are currently in phase III trials. This review provides an overview of the current therapeutic options for PsA and UC, with a focus on the JAK inhibitors.