Thrombocytopenia is often regarded as a risk factor for bleeding complications in patients undergoing percutaneous coronary intervention (PCI). The risk of mild to moderate baseline and acquired thrombocytopenia on bleeding and thrombotic or thromboembolic complications in patients with atrial fibrillation on oral anticoagulation therapy undergoing PCI, however, remains largely unknown. Management of Patients With Atrial Fibrillation undergoing Coronary Artery Stenting is a multicenter European prospective registry enrolling patients with atrial fibrillation undergoing PCI. We assessed the rate of bleeding complications as defined by Bleeding Academic Research Consortium and a composite of major adverse cardiac and cerebrovascular events (MACCE) including all-cause mortality, myocardial infarction, transient ischemic attack or stroke, stent thrombosis, systemic arterial embolism, or revascularization; and a composite of any harmful event (Bleeding Academic Research Consortium and MACCE) at 12-month follow-up in 861 consecutive patients undergoing PCI. Patients were divided into those with mild to moderate baseline thrombocytopenia (platelet count <150 × 10⁹/L; n = 99) and control group (platelet count >150 × 10⁹/L; n = 762). At hospital discharge, thrombocytopenia had no effect on prescribed antithrombotic treatment, and triple therapy (vitamin K antagonist + aspirin + clopidogrel) was the most common combination in both patient groups (69% vs 73%, p = 0.40). No differences in all-cause mortality (12% vs 11%, p = 0.79), MACCE (23% vs 22%, p = 0.87), or bleeding complications (23% vs 19%, p = 0.26) were detected. Acquired in-hospital thrombocytopenia occurred in 9.7% of patients, and it was associated with similar risk of adverse outcomes compared with control group. In conclusion, mild to moderate baseline thrombocytopenia does not seem to have a clinically significant effect on bleeding or thrombotic or thromboembolic complications after PCI in these frail patients receiving multiple antithrombotic drugs.