Acne fulminans (AF) is a rare disorder marked by severe eruptions of inflamed nodules, hemorrhagic crusts, and ulcers accompanied by systemic symptoms and often laboratory abnormalities. Commonly affecting adolescent males with pre-existing acne, AF has been associated with isotretinoin therapy and elevated testosterone levels. With unknown pathogenesis, lesions frequently involve the trunk and face and are managed standardly with corticosteroids and isotretinoin. Uncontrolled or recurrent cases pose challenges due to prolonged high-dose corticosteroid use with increased scarring. In this study, we present a case of AF in a 17-year-old male unresponsive to corticosteroid and isotretinoin therapy, successfully treated with ustekinumab, an interleukin (IL)-12/23 inhibitor. The introduction of ustekinumab facilitated a controlled corticosteroid taper and isotretinoin dose escalation, resulting in significant clinical improvement of skin lesions and systemic symptoms. This case report underscores the potential of ustekinumab as a viable therapeutic option in the treatment of AF, particularly in cases where corticosteroid and isotretinoin combination therapy have proven ineffective.