Esophageal squamous cell carcinoma can easily penetrate into the esophageal wall and invade adjacent organs due to the lack of serosa. Stage cT4b tumors involving organs adjacent to the aorta, vertebral body, trachea, or bronchus were considered unresectable. For unresectable esophageal squamous cell carcinoma, radical chemoradiotherapy or chemotherapy is recommended. However, the therapeutic effect is poor. With the advent of conversion surgery, surgical resection is feasible after induction therapy for patients with esophageal tumors that are initially unresectable due to adjacent organ invasion or distant metastasis. This article reviews the research on conversion surgery for unresectable esophageal squamous cell carcinoma in recent years in order to explore the clinical application prospects of conversion surgery.