Objective To investigate the safety and efficacy of ultrasound-guided microwave ablation (MWA) for cervical metastatic lymph nodes (LNMs) from papillary thyroid carcinoma (PTC). Methods From July 2017 to October 2020, 20 patients with LNMs from PTC treated by MWA were enrolled in our study. The changes of the largest diameter, volume, volume reduction ratio (VRR) and serum Tg pre- and post-ablation were compared, and the effects of different ablation powers on the largest diameter, volume and VRR were analyzed. Results All the patients were successfully treated with MWA, and no obvious serious complications were observed during the whole ablation process. One patient developed hypocalcemia after ablation, but returned to normal within 1 week. The largest diameter and volume increased slightly at 1-month follow-up compared with pre-ablation, but the differences were not statistically significant (P > 0.05). At the subsequent 3,6,12,18,24 months and the last follow-up, the largest diameter and volume were significantly reduced compared with pre-ablation (P < 0.05). The serum Tg level after ablation was lower than that before ablation, and the difference was statistically significant (P < 0.05). There were no significant differences in the largest diameter, volume and VRR under different ablation powers (P > 0.05). Conclusion Ultrasound-guided microwave ablation is safe and effective in the treatment of LNMs from PTC. It could be regarded as a good alternative for patients with high surgical risk and those who refuse repeat surgery.