Hepatitis C virus infection may be implicated in 12.7% of ocular adnexal marginal zone lymphomas. We present the first case of an orbital-systemic mucosa-associated lymphoid tissue lymphoma that responded to hepatitis C virus medical treatment. A 62-year-old male with a right-sided orbital mass was diagnosed with stage IIA orbital marginal zone lymphoma in addition to hepatitis C virus infection based on clinical, imaging, laboratory, and histological examinations. The systemic and orbital responses were achieved 1 year after undergoing hepatitis C virus treatment with glecaprevir/pibrentasvir. The association between the hepatitis C virus infection and orbital-systemic mucosa-associated lymphoid tissue lymphoma is relevant. Accordingly, patients with orbital mucosa-associated lymphoid tissue lymphoma should be assessed for hepatitis C virus seroreactivity for therapeutic and prognostic purposes.