Ustekinumab (STELARA), a human monoclonal antibody directed against IL-12 and IL-23, is FDA-approved to treat psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis. Increasing recognition of paradoxical skin reactions induced by older biologic therapies used for inflammatory bowel diseases (IBD), such as, adalimumab and infliximab, has led to the investigation of ustekinumab for the treatment of the cutaneous and gastrointestinal manifestations of IBD. In addition, ustekinumab may show efficacy in treating paradoxical cutaneous reactions to tumor necrosis factor-alpha (TNF-α) inhibitors. A search of the Medline/PubMed database, with additional citations obtained from the references section of relevant articles, yielded 22 articles that were included in this review. Ustekinumab is a safe and effective option for treating the cutaneous manifestations of IBD, such as, metastatic Crohn's disease and pyoderma gangrenosum. It is also an effective treatment for TNF-α inhibitor-induced paradoxical skin reactions, such as, psoriasis that do not remit spontaneously or with conventional treatment. Additional studies should focus on the optimal dosing of ustekinumab for dermatologic conditions beyond psoriasis.