Patients with advanced esophageal squamous cell carcinoma (SCC) have a poor prognosis when treated with standard chemotherapy. Programmed death ligand 1 (PD-L1) expression in esophageal cancer has been associated with poor survival and more advanced stage. Immune checkpoint inhibitors, such as PD-1 inhibitors, showed benefits in advanced esophageal cancer in clinical trials. We analyzed the prognosis of patients with unresectable esophageal SCC who received nivolumab with chemotherapy, dual immunotherapy (nivolumab and ipilimumab), or chemotherapy with or without radiotherapy. Patients who received nivolumab with chemotherapy had a better overall response rate (ORR) (72% vs. 66.67%, p = 0.038) and longer overall survival (OS) (median OS: 609 days vs. 392 days, p = 0.04) than those who received chemotherapy with or without radiotherapy. In patients receiving nivolumab with chemotherapy, the duration of the treatment response was similar regardless of the treatment line they received. According to clinical parameters, liver and distant lymph nodes metastasis showed a trend of negative and positive impacts, respectively, on treatment response in the whole cohort and in the immunotherapy-containing regimen cohort. Nivolumab add-on treatment showed less gastrointestinal and hematological adverse effects, compare with chemotherapy. Here, we showed that nivolumab combined with chemotherapy is a better choice for patients with unresectable esophageal SCC.