Ectopic thyroid glands generally occur in the midline as a result of abnormal median migration. The presence of these ectopic glands, lateral to the midline is rare. Here, the authors present one case of papillary carcinoma of thyroid arising from an ectopic thyroid tissue in branchial cleft cyst presented as a swelling in lateral neck diagnosed after cystectomy. Total thyroidectomy and neck dissection were done to rule out occult primary carcinoma of thyroid. Histopathology report showed thyroid and lymph nodes were normal.