Diverticulitis is a common gastrointestinal complaint that refers to inflammation of colonic diverticula. Its incidence has increased partly due to the increase in prevalence of diverticulosis, which results from poor dietary habits and chronic constipation. An acute diverticulitis episode can vary in severity, ranging from outpatient management of mild abdominal discomfort to inpatient admission requiring emergent surgery. Some common complications associated with diverticulitis include bowel wall perforation, microperforation, abscess formation, bowel obstruction, and colonic fistulas. A lesser-known complication of diverticulitis is pylephlebitis. Pylephlebitis refers to thrombosis of the portal vein resulting from sepsis secondary to an intra-abdominal or pelvic infection. Initially thought to be most associated with appendicitis, literature has emerged that implicates diverticulitis as the most likely culprit. Less frequently, pylephlebitis can also include thrombosis of the abdominal vasculature that drains into the portal vein such as the mesenteric veins and splenic vein. Despite antibiotic therapy, mortality in patients with pylephlebitis is high as it can lead to bowel ischemia, liver failure, or liver abscesses. While antibiotic therapy is the mainstay of treatment, anticoagulation can also be used in conjunction, especially when thrombosis extends beyond the portal vein. Herein, we present a case of a patient who was diagnosed with pylephlebitis with thrombosis extension into the splenic and mesenteric veins, which resulted from an episode of severe sigmoid diverticulitis. Our patient was treated medically with antibiotics and anticoagulation and underwent a loop transverse colostomy with full recovery. He was discharged with intravenous antibiotics and long-term anticoagulation. We present this case to highlight a rare complication of an otherwise common pathology and describe our management that led to a positive outcome for this patient.