Central nervous system (CNS) involvement by multiple myeloma is a rare complication that occurs in less than 1% of cases. The purpose of this report is to highlight the unique presentation and treatment of a patient with CNS myelomatosis. A 58-year-old Caucasian woman with multiple myeloma developed subacute vision loss bilaterally and was found to have plasma cells in her cerebrospinal fluid. Using a helmet field to 25 Gy in 10 fractions, her vision was stabilized with radiotherapy. After developing right upper extremity numbness and weakness, magnetic resonance imaging revealed intramedullary spinal cord lesions from C5 to C7. She received radiotherapy to 25 Gy in 10 fractions from C4 to T1, with improvement in upper extremity strength after 15 Gy. Although CNS involvement by multiple myeloma is a rare complication, increasing awareness is necessary for clinicians to consider meningeal myelomatosis in patients with this neoplasm.