The COVID-19 pandemic has brought severe impact on language learners' emotional states and their performance in creativity. Yet, their ability to regulate emotions is crucial for everyday functioning during times of crisis. The question of how adaptive emotion regulation (ER) strategies, which help an individual maintain appropriate and stable mood states, might affect bilinguals' creativity remains unexplored. The present study investigated this issue by measuring various indicators of the psychological impact of the COVID-19 pandemic, L2 proficiency, adaptive ER strategies, and bilinguals' cognitive creativity (CC) and emotional creativity (EC) during the pandemic. Results from a sample of 235 bilingual participants who completed a battery of survey instruments showed that: (1) bilinguals' negative mood significantly increased during the pandemic compared with their mood state before the pandemic; (2) their negative mood during the pandemic was positively associated with their adaptive ER strategies; (3) L2 proficiency had a direct effect on bilinguals' cognitive flexibility, CC, and EC; (4) L2 proficiency also indirectly influenced bilinguals' CC through cognitive flexibility. These results suggest that cognitive flexibility had a simple mediation effect on the association between L2 proficiency and CC. However, the current study further found that bilinguals had different cognitive patterns in EC. L2 proficiency influenced bilinguals' EC through cognitive flexibility indirectly only when adaptive ER strategies had a moderation effect on the association between cognitive flexibility and EC. However, this moderated mediation effect was not significant in CC. The current study implies that bilinguals' adaptive ER strategies played a distinct role in bilinguals' EC during the COVID-19 pandemic.