BACKGROUND: Squamous cell carcinoma (SCC) of the thyroid is a rare condition comprising less than 1% of all thyroid malignancies. Thyroid SCC is a variant of undifferentiated thyroid carcinoma and is also associated with the tall-cell variant of papillary thyroid carcinoma (PTC) and spindle cell carcinoma. Given its aggressive clinical course, early recognition of the disease is essential to management. CASE: We report a rare case of a 67-year-old, Filipino male initially presenting with an anterior neck mass over a period of 11 months. This was accompanied by compressive symptoms, anorexia, and easy fatigability. He underwent total thyroidectomy with histopathology consistent with diffuse sclerosing variant of PTC with squamous differentiation. The patient had rapid tumor growth, tumor recurrence, nodal metastasis, and invasion of local structures within a year after his initial presentation. He underwent completion thyroidectomy and selective neck dissection and concurrent chemo-radiotherapy with a course of radiation (60 Gy in 33 fractions) and chemotherapy with Carboplatin and Paclitaxel. After 13 months of initial presentation, the patient eventually succumbed to cardiac arrest. CONCLUSION This transformation of the thyroid is an aggressive malignancy with increased mortality; hence it should be considered in cases presenting with progressive clinical behavior. Due to his aggressive disease, the patient’s nutritional status, airway protection, and immunity were compromised. A combined modality with surgery, radiotherapy, and chemotherapy to prevent disease progression may be needed due to its aggressive clinical course.