Abstract: Viral myocarditis is a rare but life-threatening complication in patients with ulcerative colitis. Management of myocarditis is primarily supportive, because there are currently no established targeted therapies. Recent studies have increasingly highlighted the association between the gut microbiota and myocarditis. Here, we report a case of acute severe ulcerative colitis complicated by cytomegalovirus and Epstein-Barr virus co-infections that led to viral myocarditis. The patient experienced rapid remission of both intestinal and cardiac symptoms following washed microbiota transplantation, suggesting this intervention may serve as a potential alternative treatment for these life-threatening conditions.