The COVID-19 outbreak has generated significant uncertainty about the future, especially for young adults. Health and economic threats, as well as more diffuse concerns about the consequences of COVID-19, can trigger feelings of anxiety, leading individuals to adopt uncertainty-reducing behaviours. We tested whether anxiety was associated with an increase in willingness to be exposed to the risk of COVID-19 infection (WiRE) using an online survey administered to 3,110 French individuals aged between 18 and 35 years old during the lockdown period (April 2020). Overall, 56.5% of the sample declared a positive WiRE. Unemployment was associated with a higher WiRE (+8.2 percentage points (pp); 95% CI +0.9-15.4 pp). One standard deviation increases in income (+1160€) and psychological state anxiety raised the WiRE by +2.7 pp (95% CI: +1.1-4.4 pp) and +3.9 pp (95% CI: +1.6-6.2 pp),respectively. A one standard deviation increase in perceived hospitalisation risk was associated with a -4.1 pp (95% CI: -6.2-2.1 pp) decrease in the WiRE. Overall, our results suggest that both the prospect of economic losses and psychological anxiety can undermine young adults’ adherence to physical distancing recommendations. Public policies targeting young adults must consider both their economic situation and their mental health, and they must use uncertainty-reducing communication strategies.