Endoscopic evaluation of acute diverticulitis has traditionally been avoided due to the concern for a high risk of perforation. Recent data in a small number of patients has demonstrated that colonoscopy in this setting may be safer than previously thought, but the benefits of early colonoscopy appear to be limited to patients with a protracted clinical course of diverticulitis while on appropriate antibiotic therapy. Colonoscopy is commonly recommended 4–8 weeks after an acute episode of diverticulitis to screen for colorectal malignancy, which may mimic diverticulitis or precipitate an episode. The risk of colorectal cancer may be elevated in patients with diverticulitis and many of the cancers found in this population are discovered within the first year after an acute episode. Colonoscopy can also help distinguish acute diverticulitis from disease mimics such as segmental colitis associated with diverticulosis (SCAD). While acute diverticulitis is largely a clinical and imaging-based diagnosis, endoscopy remains a useful tool when patients have protracted courses or atypical imaging findings, as it can elucidate alternative diagnoses such as malignancy, SCAD, or inflammatory bowel disease.