Background: Metastatic differentiated thyroid cancer (DTC) represents an advanced disease stage requiring aggressive multimodal management. Total thyroidectomy followed by radioactive iodine (RAI) ablation is the standard treatment for disease control and survival improvement. Objective: To evaluate postoperative outcomes, including disease control, recurrence, survival, and treatment-related complications in patients with metastatic DTC following RAI ablation. Methods: This retrospective observational study included 60 patients with histologically confirmed metastatic DTC who underwent total thyroidectomy followed by RAI ablation at Shaheed Suhrawardy Medical College Hospital, Dhaka. Patients were assessed for disease-free survival, recurrence rate, overall survival, biochemical response (serum thyroglobulin) and surgical complications including recurrent laryngeal nerve (RLN) palsy and hypoparathyroidism. Results: Among 60 patients, 42 (70.0%) achieved disease-free or biochemical remission, while 18 (30.0%) had persistent or recurrent disease. Recurrence was observed in 16 patients (26.7%), most commonly in cervical lymph nodes. Elevated or rising serum thyroglobulin levels were noted in 20 patients (33.3%) and were significantly associated with disease recurrence (p < 0.05). During follow-up, 2 patients (3.3%) died, while 58 patients (96.7%) remained alive at last follow-up. Postoperative complications included transient or permanent hypoparathyroidism: 12 patients (20.0%), recurrent laryngeal nerve (RLN) palsy: 5 patients (8.3%) and RAI-related sialadenitis/xerostomia: 9 patients (15.0%). Most of the complications were transient or medically manageable. Conclusion: Radioactive iodine ablation following total thyroidectomy in metastatic differentiated thyroid cancer provides satisfactory disease control and survival outcomes in a majority of patients. However, recurrence (26.7%) and postoperative complications—particularly hypoparathyroidism and RLN palsy—remain clinically significant. Serum thyroglobulin is a reliable biomarker for early detection of recurrence. Long-term surveillance is essential for optimizing outcomes in metastatic DTC.