Nursing is one of the most stressful and high-risk professions. It is important to identify the psychological problems experienced by nurses during the COVID-19 pandemic and examine the relationship between these problems to devise measures that can properly address them. This study examined mediating effect of work stress in the relationship between fear of COVID-19 and nurses’ organizational and professional turnover intentions. Using a cross-sectional research design, this study was conducted on 486 nurses working in seven hospitals in Turkey. The mean age of the participants was 35.24±6.81 and 59.9% of them were women. The Fear of COVID-19 Scale, the General Work Stress Scale, and the Turnover Intention Scale were used to collect data. A mediation model showed that fear of COVID-19 was positively associated with work stress and organizational and professional turnover intentions. The model also revealed that work stress was positively associated with organizational and professional turnover intentions. Furthermore, the results demonstrated that fear of COVID-19 did not only have a direct effect on organizational and professional turnover intentions but also had an indirect effect on it via increased work stress. Findings improve our understanding of the role of work stress in the relationship between fear of COVID-19 and organizational and professional turnover intentions. The findings are fruitful for tailoring and implementing intervention programs to reduce the adverse psychological impacts of COVID-19 on nurses.