Phlegmasia cerulea dolens is a rare but serious complication of deep venous thrombosis, which can lead to arterial compromise, tissue ischemia, and gangrene. It typically presents in an elderly population often with coexistent malignancy. There have been no reported cases in the ambulatory pediatric population. The authors report a case of a 5-year-old girl who presented with acute, extensive left lower extremity deep venous thrombosis resulting in phlegmasia cerulea dolens. Pharmacologic and mechanical interventions as described in the adult population were utilized. This case demonstrates that an aggressive, multimodal approach to phlegmasia cerulea dolens can be employed in the pediatric population and result in successful limb salvage.