The COVID-19 pandemic has a significant negative impact on people’s life and behavior. This happens due to circumstances beyond the control of people, which lead to social isolation, increase in fear, anxiety, and other negative feelings and states. However, these negative feelings and states may have not only negative consequences, but also trigger prosocial behavior as a coping strategy. Prosocial behavior online is a relatively new domain of prosocial behavior developed due to an increase in ICT use in recent decades. Prosocial behavior online is more safe and less costly than offline one, and thus can be more relevant in times of the pandemic. This research was aimed at identifying the relationship between negative emotional states actualized by the COVID-19 pandemic (fear of COVID-19, stress, anxiety, depression) and prosocial behavior online. Cross-sectional study was conducted on a Russian sample (N=215) with the help of such instruments as Scale of Prosocial Behavior in an Online Context, Fear of COVID-19 scale and DASS-21. Regression analysis has shown that fear and anxiety contributed to prosocial behavior online, while depression inhibited it. The relationship between stress level and prosocial behavior online was not statistically significant. The results are discussed considering arousal potential of different negative emotional states.