Chronic expanding hematoma (CEH) is a rare entity that poses diagnostic and therapeutic challenges due to persistent growth, risk of recurrence, and potential for blood loss anemia. The most common etiologies of CEH are trauma or surgery. It is thought to occur due to irritant effects of blood breakdown products, causing bleeding from capillaries in chronic granulation tissue. Although treatment of CEH is variable, complete surgical excision of the hematoma and its pseudocapsule is the gold standard. We present a case of a 15-year CEH that was initially treated with limited evacuation of the hematoma and cavity decortication, resulting in recurrence. Ultimately, the patient was managed with complete excision of the pseudocapsule, closure of the cavity with quilting sutures, application of an absorbable hemostatic agent, and placement of a large drain, resulting in a successful outcome. This case highlights the efficacy of a comprehensive surgical plan in addressing CEH, emphasizing the importance of pseudocapsule excision in its entirety to prevent recurrence.