This study aimed to determine the association between sleep quality and mental health in COVID-19 carriers in China and evaluate the moderating effects of perceived social support. 1283 asymptomatic COVID-19 carriers were enrolled from March 2022 to April 2022 among Ruijin Jiahe Fangcang shelter hospital in Shanghai, China. They were assessed using the Pittsburgh Sleep Quality Index (PSQI), the General Health Questionnaire (GHQ), and the Perceived Social Support Scale (PSSS) respectively. Participants had an average age of 39.64 years and 59.6 % of whom were male. In total, 34.3 % of participants presented with poor sleep quality; 41.1 % showed bad mental health. Sleep quality was positively related to mental health (r = 0.321, P < 0.001, 95 %CI = 0.267, 0.369) and social support was negatively related to mental health (r = -0.414, P < 0.001, 95 %CI = -0.457, -0.367). Meanwhile, social support played a moderating role between sleep quality and mental health (β = 0.066, P < 0.05, 95 %CI = 0.016, 0.117). These findings indicate that mental health resulting from the COVID-19 pandemic are increasingly apparent in China and provide a focus on sleep quality for the early prevention of mental health in asymptomatic carriers. And social support may be beneficial to the improvement of mental health, especially for people in crisis (e.g., COVID-19 pandemic).© 2024 The Authors. Published by Elsevier Ltd.