: Although cisplatin plus 5-fluorouracil (5-FU) is the standard first-line treatment for advanced-stage esophageal squamous cell carcinoma (ESCC), carboplatin was substituted for cisplatin in cisplatin-ineligible patients. The efficacy of carboplatin plus 5-FU for advanced-stage ESCC remains unreported. : This retrospective study analyzed first-line treatment-carboplatin plus 5-FU, cisplatin plus 5-FU, or best supportive care (BSC)-in advanced-stage ESCC patients at a tertiary hospital in Thailand (2012-2022). Survival was assessed using the Kaplan-Meier method, compared via the log-rank test, and adjusted through propensity score matching. Significance was set at < 0.05. : Of 256 patients, 39.9% received carboplatin plus 5-FU, 27.7% cisplatin plus 5-FU, and 32.4% BSC. Carboplatin was significantly associated with older age, poorer performance status, more comorbidities, chronic kidney disease, and lower creatinine clearance. Median overall survival (OS) for carboplatin plus 5-FU, cisplatin plus 5-FU, and BSC was 8.05 (HR 0.31 0.23, 0.43 vs. BSC, < 0.001; HR 1.06 0.78, 1.44 vs. cisplatin plus 5-FU, = 0.7), 8.43, and 3.64 months, respectively. No significant OS difference was observed between carboplatin and cisplatin treatments after propensity score matching. Median progression-free survival (PFS) and objective response rates (ORR) showed no significant difference between carboplatin and cisplatin treatments. : Despite less favorable baseline characteristics of patients receiving carboplatin plus 5-FU, this combination exhibited comparable OS, PFS, and ORR to cisplatin plus 5-FU in real-world scenarios. Furthermore, it significantly improved OS over BSC. Consequently, carboplatin plus 5-FU should be considered as an alternative regimen, particularly for advanced-stage ESCC patients who are ineligible for cisplatin.