Survival outcomes of patients with cT4 esophageal squamous cell carcinoma (ESCC) remain extremely poor. We aimed to investigate long-term outcomes and identify prognostic factors in patients treated by definitive chemoradiotherapy (dCRT) alone or with dCRT plus salvage surgery (SALV) for cT4 ESCC. In total, 73 patients completing dCRT were analyzed. Patients achieving clinical complete response (CR) received follow-up evaluations thereafter. For patients diagnosed with clinical partial response (PR), potentially curative SALV was generally performed. Possible prognostic factors included demographic data, tumor staging, blood chemistry profiles, and esophageal stenosis. The 1- and 3-year overall survival (OS) rates of the 73 patients were 67.1% and 40.8%, respectively. Twenty-one patients (29%) achieved clinical CR with dCRT alone. Among 35 patients (48%) with clinical PR, 31 underwent SALV and 4 opted for non-surgical treatments. In the dCRT-alone group (n = 42), patients with clinical CR-PR (n = 25) showed significantly better 3-year OS than those who responded poorly to dCRT (stable or progressive) (n = 17) (67.5% vs. 0%, P < 0.001). In the SALV group (n = 31), curative SALV (n = 22, 73%) provided significantly better 3-year OS than non-curative SALV (58.7% vs. 0%, P < 0.001). Multivariable analysis revealed stenosis before dCRT (P = 0.02) and pretreatment elevated CRP (P = 0.02) to be independently associated with poor outcomes. The multimodal treatment strategy combining dCRT and SALV is rational for treating cT4 ESCC patients. When curative resection is feasible, SALV can provide good long-term survival outcome for patients who responded to dCRT but did not achieve clinical CR with dCRT alone.