Although corticosteroids are the standard first-line therapy for pulmonary sarcoidosis, long-term and high-dose use of these drugs are associated with increased risk of adverse events and high healthcare utilization costs. Treatment guidelines for pulmonary sarcoidosis indicate that off-label immunomodulators and biologics may be warranted for severe disease. Repository corticotropin injection (RCI, Acthar® Gel), a complex mixture of adrenocorticotropic hormone analogs and other pituitary peptides, is one of only two therapies approved by the US Food and Drug Administration for symptomatic pulmonary sarcoidosis and is recommended by current European Respiratory Society treatment guidelines for use on a case-by-case basis. With its unique anti-inflammatory and immunomodulatory mechanism of action through activation of melanocortin receptors in various cell types, RCI has demonstrated steroid-sparing properties. RCI has a long history of use in autoimmune and inflammatory disorders, with proven safety and efficacy for pulmonary sarcoidosis. In this narrative review, we present the clinical evidence for the safety and efficacy of RCI in the treatment of pulmonary sarcoidosis, identify where RCI falls within the current treatment guidelines, and describe the unique mechanism of action of RCI for promoting anti-inflammatory and immunomodulatory effects.