BackgroundDuring the COVID-19 pandemic, physical and mental health of the nurses is greatly challenged since they work under unprecedented pressure and they are more vulnerable to the harmful effects of the disease.AimTo examine the impact of the COVID-19 pandemic on nurses’ burnout and to identify associated risk factors.MethodsWe followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines for this systematic review and meta-analysis. PubMed, Scopus, ProQuest and pre-print services (medRχiv and PsyArXiv) were searched from January 1, 2020 to November 15, 2020 and we removed duplicates. We applied a random effect model to estimate pooled effects since the heterogeneity between results was very high.FindingsFourteen studies, including 17,390 nurses met the inclusion criteria. Five standardized and valid questionnaires were used to measure burnout among nurses; Maslach Burnout Inventory, Copenhagen Burnout Inventory, Professional Quality of Life Scale version 5, Mini-Z, and Spanish Burnout Inventory. The overall prevalence of emotional exhaustion was 34.1% (95% confidence interval [CI]: 22.5-46.6%), of depersonalization was 12.6% (95% CI: 6.9-19.7%), and of lack of personal accomplishment was 15.2% (95% CI: 1.4-39.8%). The following factors were associated with increased nurses’ burnout: younger age, higher educational level, higher degree, decreased social support, having a relative/friend diagnosed with COVID-19, low family and colleagues readiness to cope with COVID-19 outbreak, increased perceived threat of Covid-19, longer working time in quarantine areas, working in a high-risk environment (a COVID-19 designated hospital, a COVID-19 unit, etc.), working in hospitals with inadequate and insufficient material and human resources, decreased working safety while caring for COVID-19 patients, increased workload, decreased self-confidence in self-protection, and lower levels of specialized training regarding COVID-19, job experience, and self-confidence in caring for COVID-19.ConclusionNurses experience high levels of burnout during the COVID-19 pandemic, while several sociodemographic, social and occupational factors affect this burnout. Several interventions need to be implemented to mitigate mental health impact of the COVID-19 pandemic on nurses, e.g. screening for mental health illness and early supportive interventions for high-risk nurses, immediate access to mental health care services, social support to reduce feelings of isolation, sufficient personal protective equipment for all nurses to provide security etc. Governments, health care organizations and policy makers should act in this direction to prepare health care systems, individuals and nurses for a better response against the COVID-19 pandemic.