Alopecia universalis (AU), an advanced form of alopecia areata (AA), is a condition characterized by the complete loss of hair over the entire skin surface. Recent progress has significantly enhanced our understanding of the pathogenesis of AU. In particular, interferon-γ (IFN-γ) and interleukin (IL)-15 seem to play a pivotal role in the pathogenesis of the disease. Nonetheless, a variety of medications has been used to treat the disease with frequently inconsistent results. Given the broad modulation of the immune system and inhibition of key molecules, including IFN-γ and IL-15, oral janus kinase (JAK) inhibitors represent a treatment option for moderate to severe cases of AA, as demonstrated in case reports supporting their efficacy and tolerability. We present the case of a patient suffering from psoriatic arthritis and AU who experienced a sudden improvement in peripheral arthritis and AU while receiving JAK1 selective treatment with upadacitinib. So far, there are very limited case reports of successful upadacitinib treatment for patients with AA, mostly in patients also suffering from atopic dermatitis. Thus, we provide evidence for the efficacy of upadacitinib in managing AU in adults, also in the context of an inflammatory arthritis such as psoriatic arthritis.