Gastrointestinal (GI) bleeding from the colon is a common reason for hospitalization and is becoming more common in the elderly. While most cases will cease spontaneously, patients with ongoing bleeding or major stigmata of hemorrhage require urgent diagnosis and intervention to achieve definitive hemostasis. Colonoscopy is the primary modality for establishing a diagnosis, risk stratification, and treating some of the most common causes of colonic bleeding, including diverticular hemorrhage which is the etiology in 30% of cases. Other interventions, including angiography and surgery, are usually reserved for instances of bleeding that cannot be stabilized or allow for adequate bowel preparation for colonoscopy. We discuss the colonoscopic diagnosis, risk stratification, and definitive treatment of colonic hemorrhage in patients presenting with severe hematochezia.