Abstract: With the widespread useof immune checkpoint inhibitors (ICIs) in the treatment of various solid tumors, immune-related adverse events have attracted increasing clinical attention. Although ICI-associated myocarditis is rare, it typically has an insidious onset, progresses rapidly, and carries a high mortality rate, making it one of the most severe complications of ICI therapy. Early recognition and management remain challenging due to the absence of standardized diagnostic and therapeutic guidelines. ICI-associated myocarditis is characterized by the following features, with symptom onset commonly occurring within weeks of initiating ICI therapy. Its clinical manifestations are often non-specific and can be misdiagnosed as coronary artery disease or viral myocarditis. Prompt administration of high-dose corticosteroids combined with immunosuppressants, cardiac rhythm and functional support, is crucial for effective management. Although numerous studies highlight the importance of early detection and multidisciplinary collaboration, there is still no consensus on standardized treatment protocols. This report describes a case of acute ICI-associated myocarditis with ovarian cancer who developed symptoms after receiving combined apalutamide and toripalimab therapy. The patient responded well to corticosteroid pulse therapy, second-line immunosuppressants, and intensive care support. Due to recurrent ventricular arrhythmias, an implantable cardioverter defibrillator was placed, and cardiac function remained stable during follow-up. Through this case and a review of the relevant literature, we discuss the clinical features, comprehensive treatment strategies, and long-term management approaches for ICI-associated myocarditis, aiming to raise clinical awareness, promote standardized multidisciplinary team collaboration, and ultimately improve patient outcomes.