Gastrointestinal stromal tumors (GISTs) form commonly in the stomach, small intestine, colorectum, and esophagus. Metastatic GIST occurs in up to 50% of patients at presentation. The liver and peritoneal cavity are the most common (93%) metastatic sites; head and neck metastases are extremely rare. This report describes a unique case of a 77-year-old man who was diagnosed with a duodenal GIST that had been completely resected 15 years ago. Eleven years after complete resection, he presented with liver metastases and then received multiple lines of systemic therapy and ablative radiotherapy. In 2015, he presented to our oral and maxillofacial surgery department with a left exophytic maxillary mass that filled the left maxillary sinus. Incisional biopsy confirmed metastatic GIST. Further evaluation revealed extensive metastases in the patient's liver, lungs, spleen, abdominal wall, and lymph nodes. After adequate staging, the patient's condition was deemed palliative, and he was referred to the radiation oncology department for palliative treatment of the symptomatic maxillary lesion. To our knowledge, this is the first reported case of maxillary metastasis from a duodenal GIST. Inclusion of GIST in the differential diagnosis of jaw tumors in patients with nonoral malignancies is recommended. The literature on oral metastasis of GIST is reviewed and discussed in this case report.