Immune-related adverse events (irAEs) caused by immune checkpoint inhibitors (ICIs) are associated with improved treatment efficacy in certain types of cancer. In the present study, we assessed the association between irAEs and ICI efficacy. Patients with esophageal squamous cell carcinoma (ESCC) who received ICI treatment were stratified into irAEs and non-irAE groups. The objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) were used to evaluate the therapeutic efficacy of ICIs. Of the 78 ICI-treated ESCC patients, 39 developed irAEs. The median OS and PFS for all patients were 600 and 300 days, respectively. Median OS (P<0.001) and PFS (P<0.001) times of the patients with irAEs were longer than those in the non-irAE group. In addition, the DCR of the irAE group was higher than that of the non-irAE group (P=0.006). Univariate analysis indicated that the non-irAE group was associated with a relatively shorter OS [hazard ratio (HR)=3.687, 95% CI, 1.974-6.888, P<0.001] and PFS (HR=2.967, 95% CI, 1.691-5.204, P<0.001). The multifactorial analysis demonstrated that irAE status was an independent predictor of PFS (HR=3.564, 95% CI, 1.786-7.114, P<0.001) and OS (HR=3.288, 95% CI, 1.636-6.606, P=0.001). In conclusion, the present study demonstrated that irAEs could be used to predict improved treatment efficacy in patients with ESCC who received ICI therapy.