BACKGROUND Postoperative atrial fibrillation (POAF) occurs frequently following cardiothoracic surgery and is associated with a higher mortality and a longer hospital stay. The condition is less studied following noncardiothoracic surgery as well as emergency surgery. OBJECTIVE The aim of this systematic review was to investigate the occurrence of atrial fibrillation following emergency noncardiothoracic surgery and associated risk factors and mortality. DESIGN We conducted a systematic review according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Observational studies and randomised controlled trials were assessed for risk of bias using the Downs and Black checklist and Cochrane Handbook for Systematic reviews of intervention. DATA SOURCES A systematic literature search of PubMed, EMBASE and Scopus was carried out in August 2019. No publication date- or source restrictions were imposed. ELIGIBILITY CRITERIA Observational and randomised controlled trials were included if data on POAF occurring after an emergency, noncardiothoracic, surgical intervention on adult patients could be extracted. RESULTS We identified 15 studies eligible for inclusion covering orthopaedic-, abdominal-, vascular-, neuro- and miscellaneous noncardiothoracic surgery. The occurrence of POAF after emergency noncardiothoracic surgery ranged from 1.5 to 12.2% depending on type of surgery and intensity of cardiac monitoring. Studies that investigated risk factors and associated mortality found emergency surgery and increasing age to be associated with risk of POAF. Moreover, POAF was generally associated with an increase in long-term and short-term mortality. CONCLUSION In this study, atrial fibrillation occurred frequently, especially following emergency orthopaedic, vascular and neurosurgery. Emergency surgery and age were independent risk factors for developing atrial fibrillation. POAF seems to be related to a higher risk of postoperative complications and mortality, though further studies with long-term follow-up are needed. TRIAL REGISTRATION CRD42019112090.