OBJECTIVES: This study aimed to evaluate the long-term efficacy and safety of microwave ablation (MWA) for solitary T1N0M0 papillary thyroid carcinoma (PTC) and compare them between T1a and T1b disease. MATERIALS AND METHODS: This retrospective study included 136 patients with solitary T1N0M0 PTC who were treated with MWA and followed up for more than 5 years. Outcomes were compared between patients with T1a and T1b disease. The primary outcomes were disease progression and disease-free survival (DFS). The secondary outcomes included the volume reduction rate (VRR), the rate of complete disappearance, and complications. RESULTS: During a mean follow-up period of 70.6 ± 10.5 months, the overall disease progression rate was 5.88%. The incidences of lymph node metastases (LNMs) and new tumors were 2.21% and 5.15%, respectively. No patient was diagnosed with local recurrence, distant metastasis, or death due to PTC. There were no significant differences between the T1a and T1b groups in terms of disease progression (3.81% vs 12.90%, p = 0.15), LNMs (1.90% vs 3.23%, p = 0.54), or new tumors (2.86% vs 12.90%, p = 0.08). The 5-year DFS rate was 94.85%, the VRR was 99.7% ± 2.0%, and 97.79% of the tumors disappeared. Hoarseness occurred in five patients (3.68%). CONCLUSION: MWA is a long-term effective and safe option for patients with solitary T1N0M0 PTC, providing a minimally invasive alternative for those who refuse surgery or active surveillance. KEY POINTS: Question MWA, as a minimally invasive alternative for treating PTC, lacks comparison with surgical resection and active surveillance. Findings MWA resulted in overall disease progression in 5.88% of patients with solitary T1N0M0 PTC over more than 5 years of follow-up. Clinical relevance MWA is a safe, effective, and minimally invasive treatment for solitary T1N0M0 PTC, with high DFS rates and low complication rates, benefiting patients seeking alternatives to surgery or active surveillance.