Introduction The role of postoperative chemotherapy (POCT) in pathologic T3N0M0 thoracic esophageal squamous cell carcinoma (TESCC) has not been well addressed. The purpose of this study was to investigate the impact of postoperative adjuvant chemotherapy on survival, recurrence, and toxicities in pathologic T3N0M0 TESCC. Methods This study included 582 patients with pT3N0M0 TESCC who were treated at Sichuan Cancer Hospital from January 2009 to December 2017. The patients were divided into two groups: surgery plus postoperative chemotherapy group (S + POCT), and surgery group (S group). Propensity score matching was used to create patient groups that were balanced across several covariates (n = 236 in each group). Outcome measures included overall survival (OS) and disease-free survival (DFS). Results After PSM, both groups have balance factors. S + POCT have significantly improved the 5-year OS and DFS (OS, 70.8% vs. 52.8%, p <0.0001; DFS, 66.5% vs. 50.2%, p < 0.0001). Multivariate Cox analyses in the matched samples revealed that S + POCT were independently associated with longer OS (hazard ratio (HR) = 0.56, 95% confidence index (CI) 0.41-0.77, p < 0.0001) and longer DFS (HR = 0.60, 95% CI 0.45-0.82, p = 0.001) than surgery alone. Subgroup analyses showed that prognostic effect of POCT was significantly influenced by the number of resected lymph node (<= 20) and pStage IIB but not influenced by the number of node > 20 and pStage IIA. Conclusions Postoperative adjuvant chemotherapy is strongly associated with improved OS and DFS in patients with pT3N0M0 TESCC. A multicenter, randomized, phase III clinical trial is warranted to confirm these findings.