Hanfu, an attire newly reinvented by China's youth, has been revived as traditional Chinese attire and further reconstructed as a symbol of China's emerging cultural identity. During the COVID-19 outbreak in 2020, the annual National Costume Day, launched in 2018 by the Chinese Communist Youth League, transitioned into an online event on Bilibili, an emerging media platform in China. Known as the online Hanfu ceremony, this National Costume Day comprised self-produced short films contributed by Hanfu supporters who created videos during the lockdown. This article employs a case study approach focusing on the online Hanfu ceremony to delve into the impacts of such an event in the wake of a national health crisis. Its results indicate that Hanfu served as an affective apparatus to gather Chinese people online, evoking feelings of nationalism through the notion of cultural confidence. By assembling as a community online via Bilibili, younger Chinese people were able to experience a sense of belonging and affective moments of attachment. Such positive affective sentiments provided solace and cohesion, aiding individuals in navigating the collective ordeal of COVID-19, thereby serving the nation through configuring Hanfu as an affective apparatus—a tool for constituting solidarity.