Background: Adverse childhood experiences (ACEs) increase the risk for mental health problems. However, there is a lack of data targeting the role of ACEs for one of the most prevalent mental health problems in health-care professionals: burnout. Objective: We aimed to assess the relationship between ACEs and the core burnout dimension ‘emotional exhaustion’ (EE). As health-care professionals have been facing particular challenges during the COVID-19 pandemic, we furthermore aimed to assess the role of COVID-19 associated burden in the interplay between ACEs and EE. Methods: During the first lockdown in Germany, a total of 2500 medical healthcare professionals were questioned in a cross-sectional online survey. Questions targeted, among others, sociodemographics, ACEs, COVID-19-associated problems (e.g. increase of workload, worries about relatives and patients) and emotional exhaustion, measured by the respective dimension of the Maslach Burnout Inventory (MBI). Results: In German health-care professionals, ACEs were associated with a higher EE score. The number of experienced ACEs was associated with the majority of assessed COVID-19-associated problems. An increasing number of ACEs predicted higher EE scores, controlling for gender. The association between ACEs and EE was mediated significantly by COVID-19-associated problems. These included maladaptive coping strategies such as increased smoking, drinking and use of antidepressants/tranquilizers, feeling less protected by measures of the employee or the state, a greater feeling of being burdened by COVID-19-associated problems and greater exhaustion and sleep problems. Conclusion: Our findings suggest ACEs as significant risk factor for EE in German health-care professionals. The current pandemic means a significant burden that further pronounces this risk.