Melanoma survival has greatly improved with the advent of immunotherapy, but unequal access to these medications may exist due to nonmedical patient factors such as insurance status, educational background, and geographic proximity to treatment. We used the National Cancer Database to assess patients with nonmetastatic cutaneous melanoma who underwent surgical resection and sentinel lymph node biopsy (SLNB) with tumor involvement from 2015 to 2020. We evaluated rates of adjuvant immunotherapy among this patient population based on patient, tumor, and facility variables, including insurance status, socioeconomic status, pathologic stage (IIIA-IIID), and treatment facility type and volume. Adjuvant immunotherapy was associated with improved survival for stage III melanoma, with a slight increase in 5-year OS for stage IIIA (87.9% vs. 85.9%, P=0.044) and a higher increase in stages IIIB-D disease (70.3% vs. 59.6%, P<0.001). Receipt of adjuvant immunotherapy was less likely for patients who were older, low socioeconomic status, or uninsured. Low-volume and community cancer centers had higher rates of adjuvant immunotherapy overall for all stage III patients, whereas high-volume and academic centers used adjuvant immunotherapy much less often for stage IIIA patients compared with those in stages IIIB-D. Our results demonstrate inconsistent use of adjuvant immunotherapy among patients with stage III melanoma despite a significant association with improved survival. Notably, there was a lower use of adjuvant immunotherapy in patients of lower SES and those treated at high-volume centers. Equity in access to novel standards of care represents an opportunity to improve outcomes for patients with melanoma.