Virtual influencers are increasingly recognized as powerful tools in digital marketing engagement. Understanding the factors that influence audience engagement with virtual influencer content is important for developing effective marketing strategies. Therefore, this study conducts a theory-based investigation into the mechanisms of emoji usage in virtual influencer posts to better understand the core principles driving audience engagement. Given that virtual influencer marketing introduces additional complexity through brand management and the emotional valences of post textual content, this research aims to explore, analyze, and critically evaluate the relationship between emoji usage and audience interaction through the construction of theoretical propositions. Key constructs affecting engagement behavior, including emoji presence, content sentiment, and brand management are discussed and relevant propositions are developed and tested. Four theoretical propositions are developed, revealing complex moderation and interaction effects among emoji usage, brand management, and content sentiment, extending social media engagement theory to the virtual influencer context.