The COVID-19 outbreak has challenged the global tourism economy. It has particularly threatened the survival of tourism firms in developing countries especially those with the greatest growth of international visitors, such as Vietnam. This study aims to highlight the impact of COVID-19 on tour operators in Vietnam and explore their strategic responses to the crisis. Data were obtained from a recent survey initiated by the National Tourism Advisory Board and 32 in-depth interviews with managers of selected firms. The survey results demonstrate that the key influences of COVID-19 include plummeting revenue, increased costs, and employee redundancy. Furthermore, the majority of tour operators are aware of the need for restructuring and expect financial support from the government to overcome the crisis. The findings from the interviews reveal that tour operators focus more on short and medium-term strategies (i.e., retrenchment, persevering, and exiting) rather than long-term planning (i.e., innovating) in response to COVID-19. This study advances the knowledge and application of response-to-crisis strategies in tourism research, and its findings have practical implications for managers and policymakers in times of exceptional crisis like the COVID-19 pandemic.