Multiple myeloma is a hematologic malignancy frequently presenting with spinal lytic lesions. The authors report the case of a patient with an extensively destructive osteolytic MM lesion in the cervical spine treated exclusively with radiotherapy. Computed tomography and magnetic resonance imaging scans showed an arrest of further progression of instability and resolution of the lytic lesion, showing signs of new bone formation. Whereas surgery should be considered for cases of spinal instability and potential neurological injury, this case demonstrates that isolated radiotherapy can be used in select cases to treat MM lesions and restore the structural integrity of the spinal elements.