The frequency of concurrent thyroid cancer in patients with primary hyperparathyroidism (pHPT) varies. While the pathological association between thyroid and parathyroid disorders is frequently noted, the co-occurrence of parathyroid adenoma and papillary thyroid cancer is exceptionally rare. Furthermore, the occurrence of an ectopic parathyroid adenoma in the retropharyngeal space is exceedingly rare. Ectopic parathyroid glands present considerable complexities in both diagnosis and surgical management, especially within the realm of surgical intervention. The potential inability to accurately identify and excise ectopic parathyroid adenomas during the initial surgery may lead to an increased morbidity and recurrence, requiring high-risk reoperations. Therfore, the evaluation of anatomical variations through the utilization of relevant diagnostic tools plays a crucial role in guiding decisions pertaining to clinical manifestations, diagnostic methods, surgical interventions, and operative strategies for parathyroid tumors. We present the case of a 51-year-old female patient with papillary thyroid carcinoma in the right thyroid lobe and an ectopic parathyroid adenoma in the retropharyngeal space confirmed through surgical intervention. This case sheds light on the unusual occurrence of an ectopic parathyroid adenoma in the retropharyngeal region within a thyroid cancer patient, providing valuable insights within the realm of thyroid malignancies.