The COVID-19 crisis has had severe adverse psychological effects on people globally. Although previous research has shown that mindfulness helps people cope with stressful situations, we do not know whether mindfulness can help people cope with the effects of the pandemic. This research examined the effect mindfulness has on emotional exhaustion on the part of employees who work at private international universities in Thailand that are affected by COVID-19. Grounded in the Conservation of Resources (COR) theory, this research proposed that the level of psychological hardiness mindful employees have mediates the effect of mindfulness in reducing emotional exhaustion. The Job Demands-Resource (JD-R) model was used as an additional theory to test the moderating effect of workload, which may reduce the benefit mindfulness has in alleviating emotional exhaustion. Questionnaire survey data were collected from 300 employees at two universities. Data analysis was conducted using partial least squares structural equation modeling, and the model showed that psychological hardiness mediated the effect mindfulness has on emotional exhaustion fully. Further, the analysis supported the moderating role workload plays in suppressing the effect of psychological hardiness on emotional exhaustion significantly. A simple slope analysis indicated as well that the negative association between psychological hardiness and emotional exhaustion was present only in employees with light workloads. By integrating the principle of COR theory with the JD-R model, this research extended previous research by showing that mindfulness may not help employees cope with stress during an organizational crisis like COVID-19 when they have to manage a heavy workload.