Burnout affects physical and psychological health and is considered a major public health threat. The COVID-19 pandemic brought numerous social and economic challenges to organizations across the different work sectors, enhancing the risk of workers experiencing Burnout. However, the influence of the COVID-19 pandemic on the study of Burnout Syndrome remains unclear. To address this challenge, we analyzed pre-pandemic and post-COVID-19 outbreak research trends in this field. A comparative bibliometric analysis was conducted for the pre-pandemic period (01/2015 to 12/2019) and after the COVID-19 outbreak (01/2020 to 06/2021). Twelve thousand eighty-one publications were analyzed. Exponential growth in annual research activity on this subject was found since the COVID-19 outbreak. After 2020, the keyword “COVID-19” is often associated with “Burnout”, showing a clear international focus on this field. Research output disparities among the most affected countries have been found, with increased publications in countries such as the United States of America, China, Spain and Italy, while others have understudied this subject (e.g., India, Brazil, France). Further bibliometric analyses in this scope are recommended.