Primary melanoma of the pineal gland is a rare disease entity with an overall poor prognosis. Limited data exist to appropriately guide treatment decisions. Historical case reports have showed some success using a combination of surgical resection, radiotherapy, and chemotherapy, but long-term survival has been exceedingly rare. This report presents a female patient with a primary pineal melanoma who underwent subtotal resection followed by adjuvant focal radiation to the residual tumor. Immunohistochemistry identified a strong positivity for PD-L1 (70%). After radiation, systemic therapy with pembrolizumab was initiated with the plan to treat until progression. She has now completed 33 cycles of pembrolizumab without interruptions, complications, or disease progression. At the time of writing, the patient has had an excellent clinical outcome, with a durable near-complete response of >138 weeks. To our knowledge, this is the first patient with a pineal melanoma to be managed by targeting PD-L1. Furthermore, she has achieved the second longest overall survival and the longest progression-free survival reported in the literature.