BACKGROUND: High bleeding risk (HBR) is associated with an increased risk of both ischemic and bleeding events and is known to have a worse prognosis than non-HBR in patients with acute myocardial infarction. However, data regarding the prognostic impact of complete revascularization (CR) in acute myocardial infarction and multivessel disease patients complicated by HBR remain limited. METHODS: A total of 13 460 patients with acute myocardial infarction and multivessel disease who underwent successful percutaneous coronary intervention for infarct-related artery were selected from the nationwide Korean registry from 2011 to 2020. Primary outcome was major adverse cardiac and cerebrovascular events during 3 years of follow-up. RESULTS: Of the 13 460 patients, 4401 (32.7%) were classified as the group with HBR according to modified Academic Research Consortium-HBR criteria and 1577 patients (35.8%) underwent CR. Among the group without HBR, 3911 patients (43.2%) underwent CR for noninfarct-related artery. The group with HBR had significantly higher risk of major adverse cardiac and cerebrovascular events (non-HBR versus HBR; 16.4% versus 35.7%; adjusted hazard ratio [HR], 1.70 [95% CI, 1.56-1.85]; P<0.001) and Bleeding Academic Research Consortium type 2 or greater bleeding (4.5% versus 10.4%; adjusted HR, 1.63 [95% CI, 1.38-1.94]; P<0.001) than the group without HBR. Patients who underwent CR were associated with lower risk of major adverse cardiac and cerebrovascular events at 3 years than those with incomplete revascularization in both groups with HBR (40.0% versus 28.1%, adjusted HR, 0.65 [95% CI, 0.55-0.75], P<0.001) and without HBR (19.0% versus 13.1%, adjusted HR, 0.71 [95% CI, 0.63-0.80], P<0.001). The incidence of bleeding events was similar between the CR and incomplete revascularization groups in both groups with HBR (10.7% versus 10.0%, adjusted HR, 1.07 [95% CI, 0.84-1.37], P=0.572) and without HBR (4.2% versus 5.0%, adjusted HR, 0.98 [95% CI, 0.78-1.23], P=0.867). CONCLUSIONS: In patients with acute myocardial infarction and multivessel disease, CR was associated with a lower risk of major adverse cardiac and cerebrovascular events compared with incomplete revascularization in both HBR and non-HBR. REGISTRATION: KAMIR-NIH; KCT-0000863, KAMIR-V; KCT-0008355.