In view of the mental health issues associated with the COVID-19 pandemic, this study draws on the theories of proactive coping and altruism to examine how knowledge sharing can be used to address employee performance and mental wellbeing. Emotional intelligence is modelled as a moderator in these relationships. Two studies were conducted in Australia and Vietnam to validate the proposed relationships. The results show that only knowledge donating has a positive effect on employee performance, whereas both types of knowledge sharing are significantly related to positive mental wellbeing. Emotional intelligence exerted significant moderation effects between knowledge donating and positive mental health in the case of Australia, and between collecting and performance in the Vietnam study. This study enriches knowledge sharing literature by integrating into position psychology. The findings have implications for practitioners to adopt a cost-effective means to address mental health and increase job performance.