Vasculitic immune checkpoint inhibitor-related adverse events (irAEs) are rare, with limited data to guide their management. Here, we present a case of a 67-year-old female with stage IV cutaneous melanoma who received first-line pembrolizumab. She had completed 21 cycles of pembrolizumab dosed at 200 mg every 21 days over 15 months when she developed fatigue, chills, decreased appetite, night sweats, nausea, diarrhea, dry cough, and chest pain. A routine, staging positron emission tomography (PET) scan revealed aortitis of the transverse aortic arch. An extensive workup was unremarkable for other causes, so her condition was labeled a grade III immune-related vasculitis. Based on this diagnosis, we started high-dose prednisone and discontinued pembrolizumab. After two months of high-dose prednisone, she developed bothersome weight gain and insomnia, leading to a switch from prednisone to tocilizumab as a steroid-sparing agent. The selection of tocilizumab was based on its routine use for giant cell arteritis which can have extracranial symptoms including thoracic aortitis. Her symptoms resolved, and subsequent PET scans showed resolution of the aortitis and no evidence of metastatic melanoma. As the indications for immunotherapy expand, rare complications are becoming more prevalent, and more data will be needed to guide their management. While there is evidence for tocilizumab use as a steroid-sparing treatment for large-vessel vasculitides due to other conditions, this is the first case of its use to treat an aortitis irAE to our knowledge. In this case, it was an effective means of treating the patient while sparing them from prolonged corticosteroids.