The incorporation of immunotherapy has transformed the treatment landscape for advanced, unresectable, or metastatic gastroesophageal cancers (GECs), with improved survival outcomes. These improvements in outcomes for advanced GECs have led to clinical trials evaluating the role of immunotherapy in patients with resectable early-stage GECs. However, there remains a high burden of morbidity and mortality, and ongoing trials utilizing novel immunotherapy agents and combinations are underway. This review summarizes the findings of previous and ongoing clinical trials related to immunotherapy for patients with early- and late-stage GECs.