Background Mucormycosis is a fulminant and rapidly progressing fungal infection associated with a high mortality rate. Mucormycosis is primarily seen in immunocompromised patients, especially those with uncontrolled diabetes mellitus (DM), and recently in coronavirus disease 2019 (COVID-19) patients. Case Presentation In this case report, we present a rare case of fatal mucormycosis in Palestine. A 34-year-old Palestinian female patient presented to the emergency department one-month post-COVID-19 infection with left facial pain. During her hospital stay, she deteriorated, with a random blood sugar level of 400 mg/dl and a hemoglobin A1c of 18% with metabolic acidosis and the appearance of swelling and black eschar on her left side of her face. Finally, she was diagnosed with mucormycosis and expired two days later. Conclusion In this unfortunate case report of mucormycosis, severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection, delayed diagnosis, misuse of corticosteroids, inappropriate use of antibiotics, and uncontrolled diabetes with ketoacidosis contributed to patient mortality and fatality. Therefore, appropriate patient assessment, rapid diagnosis, and selection of appropriate treatment are important and lifesaving.