Thyroglossal duct cysts are the most common congenital abnormality of thyroid development. Seventy percent of thyroglossal duct cysts are diagnosed during childhood and 7% are diagnosed in adulthood. Less than 1% of these cases are malignant with most being papillary in nature. It is often diagnosed incidentally after surgical excision. Incidentally discovered, well-differentiated thyroid carcinoma of the thyroglossal duct, in the presence of a clinically and radiologically normal thyroid gland, can be managed adequately by the Sistrunk operation. We present a rare case of primary papillary carcinoma of thyroglossal duct cyst, with normal thyroid gland, in a 28-year-old female that was diagnosed incidentally on histopathological examination. A Sistrunk procedure was performed on the patient to remove the thyroglossal duct cyst and patient is doing well at regular follow up.