Metastatic primary cutaneous extramammary Paget disease (EMPD) is a rare clinical entity with a 5-year survival <10% and no standard therapy. We report the first case to our knowl- edge of metastatic EMPD with treatment response to checkpoint inhibitor immunotherapy. The patient had diffusely metastatic disease and previously progressed on cytotoxic chemotherapy and a molecularly targeted agent. Treatment with four cycles of ipilimumab 1 mg/kg plus nivolumab 3 mg/kg resulted in a durable partial response lasting 7 months. Analysis of metastatic tumor tissue failed to identify known predictors of treatment response to immune checkpoint inhibitors, such as high PD-L1 expression, high tumor mutation burden, or micro- satellite instability. These findings support further investigation of immune checkpoint inhibi- tion for the management of metastatic EMPD, which currently has an abysmal prognosis and no standard therapies.