With the digitalization of production and consumption environments, consumers are no longer merely targets of marketing, but key players in creating value jointly with companies by participating in various decision-making processes. Much virtual content in particular, such as fashion shows, exhibitions, games, social activities, and shopping, which fashion brands implement in virtual worlds, cannot be completed without consumers’ active engagement and interaction. Thus, this study considers consumers’ participation in virtual content provided by fashion brands as value co-creation in virtual worlds. This study aims to examine how consumer (i.e., consumer smartness) and fashion firm (i.e., perceived intellectual capital) factors influence value co-creation behavior intention in virtual worlds. Data were collected from 410 consumers in their 20s nationwide through an online survey, and a higher-order structural equation modeling analysis was conducted to test the research model. The results showed that both consumer smartness and perceived intellectual capital positively influenced customer participation behavior and citizenship behavior intentions. Specifically, perceived intellectual capital had a greater impact on value co-creation behavior in the virtual world than consumer smartness. The findings provide empirical evidence that the fashion firms’ intangible assets and consumers’ competence in the digital shopping environment encourage their intentions to co-create value in virtual worlds.