We report four studies (N=1419) examining emotional reactions from March to April 2020, when COVID-19 exhibited exponentially increasing infections and fatalities. Specifically, we examined associations between emotions with self-reported intentions to enact virus-prevention behaviors that protect oneself from COVID-19 and eudaimonic functioning. Study 1A, 1B, and Study 2 provided naturalistic evidence that mixed emotions predicted legitimate virus-prevention behaviors and eudaimonic functioning in the USA and Singapore, and Study 2 also supported receptivity as a mediator. Finally, Study 3 provided experimental evidence that mixed emotions causally increased legitimate virus-prevention behaviors relative to neutral, positive emotion, and negative emotion conditions, whereas eudaimonic functioning was increased only relative to the neutral condition. Across all studies, positive and negative emotions were unrelated to legitimate virus-prevention behaviors, while relationships with eudaimonic functioning were inconsistent. While self-reported measures do not represent actual behaviors, the findings suggest a potential role for mixed emotions in pandemic-related outcomes.