BACKGROUND: The COVID-19 pandemic has harshly burdened the healthcare systems. Health care workers (HCWs) are at substantial risk of infection and confronted several stressors as well leading them to experience burnout. This study aimed to assess the prevalence of burnout among Lebanese health HCWs and to identify its associated factors. METHODS: A cross-sectional online survey was conducted between the first of November and the end of December 2020 among Lebanese HCWs working in all active hospitals operating across the country. Data were collected using an Arabic, anonymous, self-reported questionnaire comprising four sections: (a) basic sociodemographic characteristics, (b) exposure to COVID-19 covariates, (c) occupational factors, and (d) the measurements including the Copenhagen Burnout Inventory (CBI). CBI subscale cut-off score of 50 was used to assess the prevalence of burnout among HCWs. Multinomial logistic regression analyses were performed to examine the factors associated with the different aspects of burnout. RESULTS: Out of the 1751 respondents, personal burnout (PB) was detected in its moderate and high-level aspects among 86.3% of Lebanese HCWs. Moderate and high levels of work-related burnout (WB), and client-related burnout (CB) hit 79.2% and 83.3% of HCWs, respectively. HCWs who were females, married, physicians, having a poor health status and specific living conditions (dependent child, elderly at home, family member with comorbidities, and a low income) were more likely to exhibit a high level of PB compared to no/low burnout level. Moreover, frontline HCWs, those infected by COVID-19 or those having a colleague infected by COVID-19, and those exhibiting a high perception of threat were more prone to experience a high-level PB rather than a low/no burnout. Working in a public hospital, extensive working hours, and insufficient sleeping hours were also found positively associated with high PB. However, older age and altruism were negatively associated with high PB compared to no/low PB among HCWs. As for WB, similar factors were found either positively or negatively associated with a high level of WB except health status and living conditions factors (dependent child or family member). As for CB, older age of HCWs (> 30 years) and altruism were negatively associated with high CB compared to no/low burnout level. However, working in the frontline, high threat perception, extensive working hours, insufficient sleeping hours, and low income were positively associated with high CB among HCWs compared to no/low burnout. CONCLUSION: The prevalence of burnout among Lebanese HCWs during the pandemic was significant and alarming. Enacting and implementing preventive policies and effective interventions are urgently needed to cultivate wellness among HCWs.