Objective: Since the onset of the coronavirus disease 2019 (COVID-19) pandemic, COVID-19 vaccination has substantially reduced mortality and hospitalization rates worldwide, with rare adverse events reported in clinical settings. Herein, we present a case of acute pancreatitis complicated by diabetic ketoacidosis (DKA) following the third COVID-19 vaccination dose.Patient: A 72-year-old male with a history of diabetes mellitus developed generalized fatigue, mild epigastric pain, nausea, and frequent vomiting after receiving the COVID-19 vaccine.Results: Blood analysis revealed elevated levels of pancreatic enzymes, hyperglycemia, and acidemia. Computed tomography revealed evidence of acute pancreatitis, leading to a diagnosis of both DKA and acute pancreatitis. Treatment with a large volume of saline and intravenous insulin improved both DKA and acute pancreatitis. After a thorough examination, no other factors capable of causing acute pancreatitis were identified. Hence, we concluded that acute pancreatitis was induced by COVID-19 vaccination.Conclusion: Acute pancreatitis is a rare but potentially life-threatening adverse event associated with COVID-19 vaccination. Delaying the treatment or diagnosis of acute pancreatitis can increase mortality risk in patients with both acute pancreatitis and DKA. Hence, it is crucial for healthcare professionals to consider the potential occurrence of acute pancreatitis and DKA following COVID-19 vaccination.