Abstract Background/Introduction Endovascular thrombectomy (EVT) has become the standard of care for the management of acute ischaemic stroke, but the risk of intracerebral haemorrhage and mortality still remains common following ischaemic stroke. The effect of concomitant atrial fibrillation (AF) on clinical outcomes in patients with acute ischaemic stroke after receiving EVT remains unclear. Purpose To investigate associations between AF and intracerebral haemorrhage (ICH) and all-cause mortality at 90 days in patients with ischaemic stroke undergoing EVT. Methods A retrospective cohort was conducted using TriNetX, a global health research network. The network was searched for people aged ≥18 years with ischaemic stroke, EVT and AF recorded in electronic medical records between 01/09/2018 and 01/09/2021. These patients were compared to controls with ischaemic stroke, EVT and no AF. Propensity score matching for age, sex, race, comorbidities, National Institutes of Health Stroke Scale (NIHSS) scores, and prior use of anticoagulation was used to balance the cohorts with and without AF. Results In total 1,388 patients were identified with history of ischaemic stroke treated by EVT. After propensity-score matching, 832 patients (mean age 68±13; 47% female) with ischaemic stroke, EVT and AF, were compared to 832 patients (mean age 67±12; 47% female) with ischaemic stroke, EVT and no history of AF. In the cohort with AF, 11.5% (n=96) experienced ICH within 90 days following EVT, compared with 12.3% (n=103 patients) in patients without AF (Odds Ratio (OR) 0.92, 95% confidence interval (CI) 0.68–1.24; p=0.59). In the patients with AF, mortality within 90 days following EVT was 18.7% (n=156), compared with 22.5% in patients without AF (n=187) (OR 0.79, 95% CI 0.63–1.01; p=0.06). Conclusion In patients with ischaemic stroke undergoing EVT, AF was not significantly associated with intracerebral haemorrhage or all-cause mortality at 90-day follow-up. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship.