This study sought to investigate the safety of percutaneous left atrial appendage (LAA) occlusion for stroke prevention in patients with nonvalvular atrial fibrillation who have LAA thrombus. From October 2010 to October 2016, LAA occlusions were performed in facilities within a Korean multicenter registry in patients without (n = 132) or with (n = 10) LAA thrombus (detected during preprocedural assessments). The incidences of periprocedural complications, including stroke, pericardial tamponade, major bleeding, and device embolization, were assessed and compared between the groups. The incidence of periprocedural complications was not significantly different between patients with and without LAA thrombus (0% vs 5% [6 of 132]; p = 0.49). During the mean 23.2 ± 17.5-month follow-up duration, 7 major adverse cardiac events occurred (1 cardiovascular death, 6 ischemic strokes), but overall event rates were not significantly different between the groups (14% vs 9%; p = 0.47). In conclusion, percutaneous LAA occlusion in nonvalvular atrial fibrillation patients with LAA thrombus may be a safe and feasible alternative to anticoagulation in select patients at a high risk of bleeding or contraindication to anticoagulation, or in whom anticoagulation failed to prevent stroke.