Background: Esophagogastric cancer (EGC) is one of the deadliest and costliest malignancies to treat. Care by high-volume providers can provide better outcomes for patients with EGC. Cost implications of volume-based cancer care are unclear. We examined the cost-effectiveness of care by high-volume medical oncology providers for non-curative management of EGC. Methods: We conducted a population-based cohort study of non-curative EGC over 2005-2017 by linking administrative healthcare datasets. High-volume was defined as >11 patients/provider/year. Healthcare costs ($USD/patient/month-survived) were computed from diagnosis to death or end of follow-up from the perspective of the healthcare system using validated costing algorithms. Multivariable quantile regression examined the association between care by high-volume providers and costs. Sensitivity analyses were conducted by varying costing horizons and high-volume definitions. Results: Among 7,011 non-curative EGC patients, median overall survival was superior with care by high-volume providers with 7.0 (IQR: 3.3-13.3) compared to 5.9 (IQR: 2.6-12.1) months (p < 0.001) for low-volume providers. Median costs/patient/month-lived were lower for high-volume providers ($5,518 vs. $5,911; p < 0.001), owing to lower inpatient acute care costs, despite higher medication-associated and radiotherapy costs. Care by high-volume providers was independently associated with a reduction of $599 per patient/month-lived (95% confidence interval: -966 to -331) compared to low-volume providers. The incremental cost-effectiveness ratio was -393. Care by high-volume providers remained the dominant strategy when varying the high-volume definition and the costing time horizon. Conclusions: Care by high-volume providers for non-curative EGC is associated with superior survival and lower healthcare costs, indicating a dominant strategy that may provide an opportunity to improve cost-effectiveness of care delivery.