Diffuse large B-cell lymphoma (DLBCL) is the most common form of non-Hodgkin’s lymphoma and can rarely present as a primary gastrointestinal malignancy. Primary gastrointestinal lymphoma (PGIL) is associated with a significant risk of perforation and peritonitis, with high rates of mortality. Here we describe a case of a newly diagnosed PGIL in a previously healthy 22-year-old male presenting for new-onset abdominal pain with diarrhea. Early hospital course was characterized by peritonitis and severe septic shock. Despite multiple surgical interventions and resuscitative efforts, the patient’s condition continued to deteriorate until cardiac arrest and death on hospital day five. A diagnosis of DLBCL of the terminal ileum and cecum was made by pathology post-mortem. The prognosis for these patients can be improved through early intervention with chemotherapy regimens and surgical resection of the malignant tissue. This report highlights DLBCL as a rare cause of gastrointestinal perforation that can culminate in precipitous multiorgan failure and death.