A 54-year-old man was admitted to our hospital with dyspnea and heart failure. Contrast-enhanced computed tomography showed a giant pelvic arteriovenous malformation (AVM) fed by the left internal iliac artery (IIA), right IIA, and inferior mesenteric artery. (IMA). The AVM was treated with selective embolization via the left IIA. Time-resolved three-dimensional phase-contrast magnetic resonance imaging (4D-flow MRI) visualized a gradual flow reduction in the left IIA, whereas the flow in the IMA and right IIA increased relatively. After four sessions, the patient experienced symptom relief and the blood level of N-terminal prohormone brain natriuretic peptide decreased. To the best of our knowledge, we present the first reported use of 4D-flow MRI to quantitatively assess flow reduction in the case of pelvic AVM after embolization.