Objective: Dietary antioxidants are associated with risk of death in cancer patients, and they were used to evaluate the prognosis of cancer patients. Dietary antioxidant index (DAI) can be used to evaluate dietary antioxidant content comprehensively; this study aimed to investigate the effect of preoperative DAI on health-related quality of life in patients with esophageal cell squamous carcinoma (ESCC). Methods: Data on dietary intakes were collected using a validated food-frequency questionnaire (FFQ). DAI was calculated for all study participants based on FFQ data of each participant. The study involved conducting several follow-up activities with patients diagnosed with ESCC to evaluate their quality of life. The approach employed in the study was to conduct a telephone interview. The EORTC Quality of Life Questionnaire-Core Questionnaire (EORTC QLQ-C30, version 3.0) and the Esophageal Cancer Module (EORTC QLQ-OES18) were used to collect data on the quality of life of the patients; all patients completed the full follow-up. Results: This prospective study was performed on 376 participants who were recruited from Fujian Cancer Hospital and First Hospital of Fujian Medical University. They all were diagnosed with ESCC. The results indicated that the time to deterioration of global health status (p = 0.043), cognitive functioning (p = 0.031), dry mouth (p = 0.019), and speech problems (p = 0.031) significantly delay in the high DAI group. Univariate and multivariate Cox regression analysis showed that global health status (HR = 0.718, 95% CI: 0.532–0.969), cognitive functioning (HR = 0.641, 95% CI: 0.450–0.913), dry mouth (HR = 0.637, 95% CI: 0.445–0.911), and speech problems (HR = 0.651, 95% CI: 0.449–0.945) were improved in the high DAI group. Conclusions: Prognostic value of preoperative DAI was significant for patients with ESCC who undergo surgical intervention. Its level was positively correlated with the postoperative quality of life of patients, which can delay and improve the occurrence of postoperative physical function and symptom deterioration.