Nasopharyngeal sarcomatoid carcinoma (SaCa) is extremely rare, and concurrent chemoradiation is the standard treatment for squamous cell-based nasopharyngeal cancer (NPC). This case report gives the first explanation of a nasopharyngeal SaCa patient treated with volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB), which is an excellent treatment modality that leads to complete response for locally advanced NPC. A 70-year-old male presented with nasal obstruction, epistaxis, and right neck node enlargements. Examination revealed an extensive tumor of nasopharyngeal tumor extending into the nasal cavity and right parapharyngeal space with bilateral lymphadenopathy on positron emission tomography (PET)–computed tomography images of focal hypermetabolic bone lesion in C4 body (stage T3N2M1). An excisional biopsy of nasopharyngeal wall mass showed a SaCa. He received concurrent chemoradiation which was VMAT and systemic chemotherapy (cisplatin 60 mg). A dose of 70 Gy was delivered to the planning target volume (PTV70) (gross tumor volume plus margin 3–5 mm) and PTV59.4(a wider margin around high-risk clinical target volume, including the clivus and neck nodes) all given in 33 fractions. Radiological examination such as magnetic resonance imaging (MRI) and PET images at the completion of external beam therapy revealed questionable residual disease. Follow-up MRI scans 4 weeks after radiotherapy revealed a complete tumor response. VMAT with SIB can be an effective treatment option for SaCa of the advanced nasopharynx.