Cancers of the gastro-oesophageal system represent the fourth most common cancer type, following lung and breast cancers. Mortality rates remain high due to late diagnosis. In the context of gastrointestinal malignancies, the tumour microenvironment and immune system play a pivotal role in cancer progression and treatment response. The role of immunotherapy in the treatment of gastroesophageal cancers has become increasingly significant in recent years. Immunotherapy, which was previously employed solely in the context of metastatic gastric cancer, has recently been established as a standard treatment modality in the adjuvant management of oesophageal cancer that has undergone neoadjuvant therapy and remains following surgical resection. Furthermore, studies are currently underway to assess the efficacy of combining immunotherapy with standard chemotherapy regimens in the neoadjuvant treatment of gastric cancer. Preclinical and clinical evidence has demonstrated the effectiveness of anti-PD1 and anti-PDL1 agents in gastroesophageal cancers, and these agents are now included in current guidelines. In addition to these agents, studies are ongoing to evaluate the potential of CTLA-4 inhibitors and vaccines in this setting.