In this article, we present a case of diffuse follicular variant papillary thyroid carcinoma with pituitary metastasis, which is a rare cause of pituitary metastasis. The follicular variant of papillary thyroid carcinoma is an uncommon variant of papillary carcinoma. A 74-year-old male was presented with weakness, fatigue, and a decreased appetite. The patient was diagnosed with secondary adrenal and thyroid insufficiencies. Imaging revealed a pituitary mass with suprasellar extension, right cavernous sinus invasion, and optic chiasm compression. Thyroid ultrasonography revealed a nodule with a maximum size of 7.2cm in the right lobe. Cytological examination via fine-needle aspiration suggested papillary thyroid cancer. Total thyroidectomy with central and right lateral neck dissection confirmed the diagnosis of diffuse follicular variant of papillary thyroid carcinoma. Owing to visual field defects, the patient underwent transsphenoidal surgery. Histological and immunohistochemical evaluations confirmed pituitary metastasis from the papillary thyroid cancer. Radioactive iodine treatment and gamma knife radiotherapy of the pituitary gland were performed. The initiation of sorafenib treatment was deemed appropriate during the follow-up. A significant decrease in the thyroglobulin levels was observed after sorafenib treatment. Pituitary metastasis should be considered in patients diagnosed with hypopituitarism and pituitary lesions at initial evaluation. The presence of visual field defects may be an indication for neurosurgical intervention and guide both diagnosis and treatment. The management of papillary thyroid cancer and the role of treatment modalities in prognosis depend on the biological behavior of the tumor. Early diagnosis and multidisciplinary management are crucial for the treatment of these patients.