To investigate independent risk factors for esophageal cancer-related ischemic stroke (ECIS) and to use them to develop an index of ECIS to help clinicians identify patients at high risk for ECIS or to identify ECIS from other types of ischemic stroke. Methods: We retrospectively enrolled active esophageal cancer (EC) patients with acute ischemic stroke (ECIS group) and patients with active EC without ischemic stroke (EC group), age-and sex-matched with ECIS patients, at seven centers from January 2011 to December 2020. Clinical data and laboratory and imaging findings were collected. Univariate and multivariate analyses were performed to analyze the independent risk factors for ECIS. Optimal cutoffs for sensitivities and specificities were obtained by Youden's J statistic following a receiver operator characteristic (ROC) analysis of each risk factor and the product of the risk factors. Results: A total of 91 ECIS patients and 91 EC patients were included. Elevated levels of carcinoembryonic antigen (CEA) [odds ratio (OR) = 0.105, 95% confidence interval (CI): 1.051-1.174, P < 0.001], D-dimer (DD) (OR = 0.003, 95% CI: 1.002-1.004, P < 0.001), and neutrophil count (OR = 0.857, 95% CI: 1.628-3.407, P < 0.001) were independent risk factors for ECIS. The area under the curve (AUC) of each independent risk factor and the product of the three independent risk factors were calculated by a receiver operator characteristic (ROC) curve, and the cutoff value from the largest AUC was called the ECIS index. Conclusion: It was suggested that elevated plasma DD and CEA levels and increased neutrophils in EC patients may altogether contribute to the development of ECIS. The index of ECIS may facilitate clinicians to identify patients at high risk for ECIS or to identify ECIS from other etiologic types of ischemic stroke.