A heterogeneous group of malignancies known as gastrointestinal ( GI ) cancers, such as esophageal, gastroeSophAGEAL junction, gastric, duodenal and distal small bowel, biliary tract, pancreatic, colon, rectal, and anal cancer, pose a sizable global burden. Immunotherapy has changed the way that some patients are treated for a variety of GI cancers, providing them with long-lasting outcomes and protracted survival. Immune checkpoint inhibitors ( ICIs ) for the treatment of metastatic disease and in the resectable setting have received tissue site-specific regulatory approvals for use as monotherapies or in combination regimens against programmed cell death protein 1 ( PD – 1 ). However, depending on the anatomic site of origin, different biomarker and histology requirements apply to ICIs in GI cancer. In addition, ICIs have distinct toxicity profiles when compared to other systemic therapies like chemotherapy, which have long been the mainstay for GI cancer. The Society for Immunotherapy of Cancer ( SITC ) gathered a panel of experts to create this clinical practice guideline on immunotherapy for the treatment of GI cancer with the aim of improving patient care by offering advice to the oncology community. The expert panel created evidence- and consensus-based recommendations for healthcare professionals using ICIs to treat GI cancers using published data and clinical experience. These recommendations covered a variety of subjects, including biomarker testing, therapy selection, patient education, and quality of life considerations.