Recent years have witnessed a boom of fashion bloggings sharing information about clothing and cosmetics on diverse social media platforms. Constant exposure to fashion-related digital information heavily impacts the cognition and behaviour of Chinese youth. Compared to the substantial studies on the impact of social media, scarce research has been conducted on how youth’s cognitive processing of fashion-related digital information interacts with motivational factors to determine the subsequent behaviour. This study made an initial attempt to address this issue by exploring the successive associations between clothing motivation (amotivation, controlled, and autonomous motivation), online critical thinking (for information credibility, objectivity, and relevance), and the subsequent behavioural intentions. A total of 1997 Chinese youths with diverse educational backgrounds voluntarily participated in the study. Results confirmed the direct links between clothing motivation and behavioural intentions, but these links were mediated by different online critical thinking skills. This study provides new insights for both practitioners and scholars in the fields of education, psychology, social media, and marketing.