Background: Kawasaki disease (KD) is a type of vasculitis in which giant coronary artery aneurysms (CAAs) can occur. There are no specific guidelines for managing giant CAAs that develop quickly and are at risk of rupture. Regarding cardiovascular drugs, only beta-blockers are formally recommended in the acute phase of KD. Case presentation: A 6-month-old male patient with multiresistant Kawasaki disease and giant CAAs that continued to enlarge after controlling systemic inflammation was examined. The patient required three doses of intravenous immunoglobulin, methylprednisolone pulses, and anakinra and infliximab to normalize systemic inflammation. Due to the rapid increment of aneurysms’ dimensions and the risk of rupture, we introduced anticoagulant therapy and propranolol plus captopril, and titration doses were introduced according to a tolerated decrease in heart rate and arterial pressure. CAAs increment stabilized and slowly reduced their dimensions. Conclusions: The authors describe an atypical case of multiresistant KD with giant rapidly increasing CAAs even after controlling systemic inflammation. The introduction of a beta-blocker and an angiotensin-converting enzyme (ACE) inhibitor was demonstrated to be useful for stabilizing giant CAAs growth and reducing the potential risk of rupture.